Japan: Regulatory Background

Japan: Regulatory Background


This page provides an overview of the regulatory agencies and the decision-making process in Japan.

Regulatory Authorities

Since 2001, Japanese emission standards for engines and vehicles and fuel efficiency targets are jointly developed by a number of government agencies, including:

Before the Japanese government was reorganized in 2001, the Ministry of Transportation (MOT) and Ministry of Commerce (MOC) oversaw emission standards. In developing engine emission standards and policies, the Ministry of the Environment relies on recommendations of its advisory body known as the Central Environment Council (CEC).


On-Road Engines and Vehicles

Japan introduced new engine emissions standards for on-road vehicles in the late 1980’s. The Japanese standards, however, remained relaxed through the 1990’s. In 2003 the MOE finalized very stringent 2005 emission standards for both light and heavy vehicles. At the time they came to power, the 2005 heavy-duty emission standards (NOx = 2 g/kWh, PM = 0.027 g/kWh) were the most stringent diesel emission regulation in the world. Effective 2009, these limits were further tightened (NOx = 0.7 g/kWh, PM = 0.01 g/kWh) to a level in-between the US 2010 and Euro V requirements.

Most categories of on-road vehicles, including passenger cars and heavy-duty trucks and buses, are also subject to mandatory fuel efficiency targets. The Japanese fuel efficiency requirements for heavy trucks and buses were the world’s first fuel economy regulation for heavy vehicles.

Off-Road Engines

The first emission regulations for new off-road engines and vehicles, known as MOT/MOC standards, were adopted by the former Ministry of Transport (MOT) and Ministry of Construction (MOC). After the reorganization of Japanese government in 2001, off-road engine emissions fell under the jurisdiction of MOE and MLIT, the same ministries that are responsible for regulating emissions from highway engines. The first MOE/MLIT standards for off-road engines were promulgated in 2005.

Marine Engines

In 2003, the MLIT proposed emission regulations for new and existing ocean-going ships. The regulations, aligned with the 1997 MARPOL 73/78 Annex VI limits (by International Maritime Organization), require cutting NOx emissions by about 10% from previous non-regulated levels.


Engine and vehicle emission standards are developed under the authority of the Air Pollution Control Law, while fuel efficiency targets are adopted under the Law Concerning the Rational Use of Energy, (Energy Conservation Law).

Automotive NOx and PM Law – In 1992, to cope with NOx pollution from existing vehicle fleets the MOE adopted the Motor Vehicle NOxLaw, which aimed at the elimination of the oldest, most polluting vehicles from in-use fleets in certain geographical areas. In 2001, the regulation has been amended to also include PM emission requirements, and renamed as Automotive NOx and PM Law.


Tokyo has established a Tokyo Metropolitan Environmental Master Plan. Important components include the Realization of Environmentally Sustainable Transport.

Tokyo Retrofit Program – The Tokyo government and several neighboring prefectures adopted diesel emission regulations, which require retrofitting of older in-use diesel vehicles with PM control devices (catalytic converters or particulate filters), or else replacing them with newer, cleaner models. The Tokyo retrofit requirements became effective in October 2003, and helped spur the adoption of more stringent national emission requirements, including the 2005 HDV standards and the revised NOx/PM Law..

Harmonization – In November 1998 Japan acceded to the “The UN/ECE 1958 Agreement” on Reciprocal Recognition of Type Approval of Motor Vehicles, that aims to promote the harmonization of regulations and reciprocal recognition of approvals.

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