Establishing a factory in Thailand involves more than finding land and buying machinery. Investors must comply with Thai industrial, environmental and safety regulations – and, in many cases, obtain a Factory Operation License (Ror Ngor 4) before starting operations.
At Lex Bangkok, we work in close cooperation with our trusted partners – licensed Thai engineers with more than 30 years of experience – to provide one-stop support for foreign and local clients setting up or expanding factory operations in Thailand.
Our integrated team combines legal, regulatory and engineering know-how so your project is compliant from day one and structured for long-term growth.
Understanding the Factory Act and Factory Definition in Thailand
The Thai Factory Act B.E. 2535 (1992) sets out the core framework for factory establishment, expansion and operation in Thailand. It covers issues such as licensing, safety, pollution control and government supervision, and is administered mainly by the Department of Industrial Works under the Ministry of Industry.
Under this law, a “factory” generally means premises where machinery of at least a certain total horsepower, or a specified number of workers, are used for activities such as producing, assembling, packing, repairing, storing or destroying goods that fall under listed industrial categories. Not every site meeting this definition requires a license – some only need to notify the authorities, while others must obtain full approval before operations can begin.
Factory Categories and Licensing Obligation
Ministerial regulations divide factories into three broad categories:
- Factories that must only notify
These factories may start operating after submitting a notification and receiving acknowledgement from the authorities. - Factories that are exempt from licensing
Certain smaller-scale factories, or those specified in ministerial rules, may operate under lighter regulatory requirements. - Factories requiring a Factory Operation License (Ror Ngor 4)
Larger factories exceeding thresholds for machinery power and number of employees must obtain a license from the Department of Industrial Works before commencing operations. In some cases, operators may be allowed to start construction based on a preliminary certificate while the full license is still under consideration.
For factories in the third category, operators must usually inform officials before test runs and again before full commercial operation begins, following the relevant ministerial procedures.
Why the Factory Operation License (Ror Ngor 4) Matters
If your project falls into the category requiring a license, a Ror Ngor 4 factory license is a legal prerequisite to operate. Without it, the business can face orders to suspend operations, fines, or other enforcement measures.
In practice, the licensing process typically involves:
- Preparing a complete factory license application
- Submitting a factory layout and site plan
- Submitting a machine list and related technical information
- Providing company and land documents
- Undergoing site inspections by government officers and, where needed, a review of environmental impact and safety measures
Because technical, environmental and legal issues are all connected, it is usually more efficient – and less risky – to handle everything through a coordinated team of lawyers and licensed engineers.
Our Integrated Industrial Services
1. Application for Factory Operation License (Ror Ngor 4)
We assist with the full factory license Thailand process, including:
- Initial assessment of whether your planned activities require a Ror Ngor 4 license or fall into another regulatory category
- Coordination with licensed Thai engineers to prepare and sign factory plans, machinery lists and safety documentation
- Preparation and review of application forms and supporting documents
- Liaison with the Department of Industrial Works and relevant authorities during inspections and follow-up queries
Our aim is to present your application in a clear, complete and compliant way to help reduce delays and avoid unnecessary revisions.
2. Operating Factory License Thailand in an Industrial Estate
Many investors prefer to locate factories inside a Thai industrial estate, where zoning, utilities and infrastructure are already designed for industrial activities. Estates may be operated by the Industrial Estate Authority of Thailand or private developers, each with its own rules on land use, construction, environmental controls and estate fees.
We support you with:
- Reviewing industrial estate rules, lease or purchase agreements and related restrictions
- Coordinating factory licensing and safety obligations connected to the estate
- Communicating with estate operators and government agencies in both English and Thai
This helps ensure you understand exactly what you can do within the estate and what ongoing obligations apply to your project.
3. Industrial Factory Layout & Machinery List for Factory License Thailand
A typical Ror Ngor 4 application must include:
- A factory layout / site plan showing buildings, production lines, utilities, access ways, storage areas and safety systems
- A machinery list, indicating the type, power and capacity of all major machines and equipment
- Plans and descriptions of waste treatment, hazard control and pollution prevention systems
Together with our engineering partners, we can:
- Prepare or review factory layout drawings for regulatory compliance and practical operations
- Prepare the machinery list in the format expected by authorities
- Align layout and machinery information with environmental, health and safety standards
All plans and lists are prepared or reviewed by properly licensed Thai engineers with extensive industrial experience.
4. Engineering, Procurement and Construction (EPC) Management
For investors who prefer a turnkey factory solution, we can coordinate Engineering, Procurement and Construction (EPC) management through our network of trusted EPC contractors.
Our involvement may include:
- Coordinating conceptual and detailed engineering design with your business and production needs
- Assisting in procurement strategy and contractor selection from a legal and risk perspective
- Reviewing EPC contracts and related documentation
- Monitoring compliance with licensing conditions, safety requirements and key project milestones
You remain in control of major decisions while we help align the legal, technical and contractual aspects of the project.
5. Factory Feasibility Study
Before committing to a major investment, a factory feasibility study helps determine whether the project is commercially, technically and legally viable.
Working closely with our engineering partners, we can support feasibility assessments that typically cover:
- Market and production assumptions
- Site selection and zoning suitability (inside or outside industrial estates)
- Preliminary factory layout and capacity planning
- High-level CAPEX and OPEX estimates
- Overview of licensing and regulatory requirements, including potential needs for EHIA (Environmental Health Impact Assessment) in more sensitive projects
This gives decision-makers a clearer view of risks, timelines and key go/no-go points.
Required Documents and Typical Procedures
While the exact list depends on your project, a factory license application commonly involves:
- Company registration documents / affidavit
- Land title deed, lease or other land-use documents
- Factory layout and construction plans
- Certified machinery list
- Environmental and safety plans (wastewater treatment, emissions control, fire safety, evacuation plans, etc.)
- Application forms and supporting statements required by the Department of Industrial Works
We help coordinate the legal and technical documents so they are consistent and ready for submission.
Timeline, Validity and Renewal of Factory Licenses
Once your application is submitted, a government officer typically visits the site to inspect the factory area, equipment and pollution-control systems. A report is then prepared and forwarded to the relevant industrial office. There is a statutory timeframe for the authorities to consider the application and issue a decision, although additional questions or required revisions can extend the process.
A factory license is generally valid for five years from the date of issuance. If the factory is relocated or the business is dissolved, the license will be treated as expired as of that date.
For ongoing operations, renewal should be requested before the license expiry date to avoid interruptions. Renewal usually involves:
- Reviewing current operations for compliance with licensing and environmental conditions
- Submitting renewed application documents and updated reports
- Cooperating with any further inspections or follow-up queries from the authorities
We can assist in planning renewals and keeping track of regulatory timelines to support uninterrupted operations.
Environmental and Safety Compliance
Thai regulations require factories to operate safely and minimize environmental impact. Depending on the type and scale of factory, key obligations may include:
- Waste and emissions control – proper treatment and discharge of wastewater, control of air emissions and solid waste management
- Hazard and pollution prevention – systems to manage hazardous substances and reduce the risk of leaks, spills or accidents
- EHIA (Environmental Health Impact Assessment) – for certain projects considered to have significant environmental impact, an EIA may be required before approval
- Safety measures and training – fire protection systems, emergency exits, evacuation plans and regular staff training
Our role is to help you understand the regulatory framework and coordinate with licensed engineers and environmental consultants so that your factory design and operations are aligned with Thai standards.
Why Work with Lex Bangkok and Our Engineering Partners?
- Legal and engineering in one team
We coordinate lawyers and licensed Thai engineers (30+ years of experience) so your factory project is reviewed from both legal and technical angles. - Foreign-investor friendly approach
We explain Thai regulations in clear, practical English and help bridge communication with local authorities and industrial estates. - Compliance from the planning stage
Early integration of factory layout, machinery, environmental and licensing strategy can significantly reduce delays, redesign costs and compliance risks later. - End-to-end support
From feasibility and site selection to Ror Ngor 4 licensing, EPC coordination and renewal, we can accompany your project through its full lifecycle.
Important: The information on this page is for general guidance only and does not constitute legal advice. Each project must be assessed on its specific facts, and you should consult a qualified Thai lawyer before making decisions.
FAQ – Factory License & Industrial Services in Thailand
Q1: Who needs a Factory Operation License (Ror Ngor 4) in Thailand?
Factories that exceed specified thresholds for machinery power and number of employees, and that fall into certain industrial categories, must obtain a Ror Ngor 4 license before starting operations. Whether your project meets these criteria depends on your industry, process and scale, so it should be checked case by case.
Q2: How long does it take to obtain a factory license?
If documents, factory plans and environmental measures are complete and clear, the authorities are expected to inspect the site and issue a decision within legally prescribed timeframes. In practice, additional questions, document revisions or environmental reviews can extend the process, so it is wise to allow several months in project planning.
Q3: How long is a factory license valid and when should I renew?
A factory license is typically valid for five years from the issuance date. Renewal applications should be filed before the expiry date to maintain continuous operations and avoid the risk of being seen as operating without a valid license.
Q4: Do I have to be in an industrial estate to get a factory license?
No. Many licensed factories are located outside industrial estates. However, industrial estates can simplify infrastructure, utilities and certain zoning issues. Whether an estate or a standalone site is better depends on your industry, logistics, cost profile and long-term strategy.
Q5: Why do I need a licensed engineer for factory plans and machinery lists?
Authorities rely on technical documents – such as layout plans, machinery lists and safety systems – to assess compliance with the Factory Act and environmental and safety regulations. These documents are usually required to be prepared or certified by licensed engineers, who are responsible for the accuracy of the technical information.
WE CAN HELP YOU IN 1-STOP SERVICE
Contact Lex Bangkok
If you are planning to set up or expand a factory in Thailand and need support with:
- Factory license Thailand (Ror Ngor 4)
- Operating in a Thai industrial estate
- Factory layout and machinery list
- EPC management for a turnkey factory project
- Factory feasibility studies and regulatory planning
You are welcome to contact Lex Bangkok for an initial discussion.
We coordinate closely with our licensed Thai engineering partners (30+ years’ experience) to provide integrated legal and technical support, helping your factory project move forward with clarity, compliance and confidence.
info@lexbangkok.com