Japan’s oil industry was built without significant domestic petroleum resources. Rather than producing crude at home, the country developed a system based on large-scale imports, coastal refineries, national storage and long-term relationships with overseas suppliers.
This model supported Japan’s industrial expansion and created a reliable domestic supply of gasoline, diesel, jet fuel, kerosene and petrochemical feedstocks. It also produced a clear strategic weakness. Almost every barrel processed in Japan must first cross international waters, and the overwhelming majority of crude comes from a small group of Middle Eastern producers.
Oil demand is now declining as the population contracts, vehicles become more efficient and electrification expands. Yet petroleum remains essential to transport, aviation, shipping, petrochemicals, heating and emergency response. Japan’s oil policy is therefore moving in two directions at once: reducing long-term consumption while protecting the import and refining system that the economy still requires.
Japan’s Oil Supply Begins in the Middle East
Domestic crude production is extremely small. In fiscal year 2024, Japan produced only about 381,000 kilolitres of crude oil, equal to approximately 0.3% of the volume processed by its refineries. This was roughly one day of national refinery throughput.
Imports therefore provide almost the entire supply. Japan imported approximately 136.3 million kilolitres of crude during fiscal year 2024. Middle Eastern producers supplied 95.9% of that total, one of the highest levels of regional concentration among major industrial economies.
The United Arab Emirates was Japan’s largest supplier, providing 43.6% of imported crude. Saudi Arabia followed with 40.1%. Kuwait and Qatar supplied most of the remaining Middle Eastern volume. Together, the UAE and Saudi Arabia accounted for more than four-fifths of Japan’s crude imports.
This concentration reflects commercial and technical realities. Gulf producers can supply large and dependable volumes under long-term arrangements, while Japanese refineries are designed to process many of the crude grades produced in the region. Japanese companies have also developed deep commercial relationships and upstream investments in countries such as the UAE.
However, a diverse list of companies does not necessarily create geographic diversity. Cargoes from several Gulf states may still depend on the same shipping route through the Strait of Hormuz. A disruption affecting that passage can therefore threaten supplies from multiple producers at the same time.
Japan has periodically imported crude from the United States, Ecuador, Southeast Asia, Australia and other markets. These flows provide alternatives, but replacing Middle Eastern oil at scale is difficult. Longer shipping distances increase costs, and crude from another region may require refiners to change operating conditions or product yields.
The country’s central supply problem is consequently not a lack of possible sellers. It is the challenge of replacing large, compatible and commercially attractive Gulf volumes quickly enough during a crisis.
Coastal Refineries Turn Imported Crude into Domestic Supply
Japan’s petroleum system is organised around domestic refining. Instead of relying mainly on imported gasoline, diesel and other finished fuels, companies purchase crude oil and process it at refineries located near major population and industrial centres.
All of Japan’s refineries are in coastal areas. This allows very large crude carriers to deliver cargoes directly to storage and processing sites while avoiding expensive inland crude transportation. Refined products can then move by coastal tanker, truck, rail or pipeline to terminals and local markets.
At the end of March 2025, Japan had 19 refineries with combined crude-processing capacity of approximately 3.11 million barrels per day. Important refining areas include Chiba, Kawasaki, Yokkaichi, Sakai, Mizushima and other industrial coastal zones.
ENEOS operates the largest share of national capacity, including major facilities at Mizushima and Kawasaki. Idemitsu Kosan, Cosmo Oil, Fuji Oil, Taiyo Oil and other companies also form part of the refining system. Several sites are integrated with petrochemical production, power generation, lubricants and other industrial activities.
Domestic refining gives Japan greater control over product quality and output. Operators can adjust the balance between gasoline, diesel, kerosene, jet fuel and petrochemical feedstocks in response to market demand. Refineries also provide an important layer of emergency flexibility because crude stocks can be processed into the products most urgently needed.
The system is not completely self-sufficient. Japan still imports products such as liquefied petroleum gas and naphtha because domestic production does not cover all demand. However, national refineries can normally supply the main transport fuels required by the domestic market.
Their importance extends beyond routine commercial operations. Following the 2011 earthquake and tsunami, damage to refining and distribution infrastructure demonstrated that fuel security depends on the entire supply chain. Crude inventories have limited value if refineries, ports, roads or local terminals cannot operate.
Companies and government agencies have since strengthened emergency planning, refinery cooperation, terminal resilience and fuel distribution arrangements. Earthquake resistance and rapid restoration remain particularly important in a country where much of the petroleum system is concentrated along exposed coastal industrial areas.
Strategic Reserves Compensate for Limited Domestic Resources
Japan cannot remove its dependence on imported oil, so it maintains one of the world’s largest emergency stockholding systems. The system combines government reserves, compulsory commercial stocks and joint storage arrangements with producing countries.
Under the national stockpiling framework, government reserves are managed against a target linked to 90 days of imports. Refiners, importers and distributors are also required to hold substantial private-sector stocks, with the standard framework based on around 70 days of domestic consumption.
These reserves serve several purposes. They can replace delayed cargoes, support refiners during international disruptions and give the government time to arrange alternative supplies. They also reduce the risk that a short-term shipping crisis immediately becomes a national fuel shortage.
Japan has supplemented traditional reserves with joint stockpiling projects involving oil-producing countries. Under these arrangements, a producer stores crude in Japanese facilities and may use the stocks commercially under normal conditions. Japan receives priority access during an emergency. The model strengthens relations with suppliers while placing usable crude close to domestic refineries.
The Middle Eastern supply disruptions of 2026 demonstrated why this system remains central to national policy. Japan reduced private stockholding requirements and began releasing government and jointly held reserves while refiners arranged alternative cargoes. Supplies from the United States and Latin America became more important, but higher transport costs and refinery compatibility remained concerns.
Emergency reserves cannot permanently replace normal imports. They are a bridge that allows time for commercial adjustments, diplomatic action and demand restraint. Their value is greatest when combined with diversified procurement, flexible refining and functioning domestic distribution.
Falling Demand Is Reshaping the Refining Industry
Japan’s petroleum demand has been declining for structural rather than temporary reasons. The population is shrinking, cars use less fuel, hybrid and electric vehicles are spreading, and industrial energy efficiency has improved. Some heating demand has also moved toward electricity and gas.
As consumption falls, maintaining excess refinery capacity becomes expensive. Operators must spread labour, maintenance and environmental costs across fewer barrels. This has encouraged refinery closures, capacity reductions, mergers and greater operational cooperation.
The number of refineries and total processing capacity have both declined over time. Companies now place greater emphasis on operating their strongest and most complex sites efficiently rather than preserving every facility.
Domestic consolidation has produced a market led by a small number of large groups. ENEOS is the largest refiner, while Idemitsu and Cosmo also hold major positions. This concentration can improve efficiency and investment capacity, but it also makes the resilience of individual facilities increasingly important.
Refiners are also changing what their sites produce. Petrochemicals, lubricants, sustainable aviation fuel, renewable diesel, hydrogen and materials for advanced manufacturing offer possible growth areas as gasoline demand contracts. Existing refinery locations have valuable port access, tanks, utilities and technical workforces that can support these new businesses.
The transition will be gradual. Japan still has a large vehicle fleet, major airlines, international shipping activity and substantial petrochemical demand. Petroleum products also remain useful during natural disasters because liquid fuels can be stored and transported without relying entirely on the electricity grid.
The challenge is to reduce capacity in line with demand without weakening emergency supply. Closing too much refining capacity could leave Japan more dependent on imported finished products, creating a different form of vulnerability.
Overseas Investment Supports Supply Security
Japan’s oil policy extends beyond buying cargoes. Japanese companies and public institutions support overseas exploration, production and infrastructure projects to obtain commercial access and strengthen relationships with producing states.
Companies including INPEX and Cosmo have interests in Abu Dhabi, while government-backed financing and diplomatic engagement support broader resource-security goals. Equity production does not guarantee that every barrel will be delivered to Japan during a crisis, but it gives Japanese firms deeper involvement in upstream decisions and long-term supply networks.
Relations with Saudi Arabia and the UAE also include storage, refining, technology and lower-carbon energy cooperation. Japan’s energy transition therefore does not mean ending ties with petroleum exporters. In many cases, those relationships are expanding into hydrogen, ammonia, carbon capture and other industries.
Diversifying beyond the Gulf remains difficult but necessary. More purchases from the United States, Latin America and other regions could lower geographic concentration, although they may also raise costs. Refinery modifications that permit a wider range of crude grades would increase flexibility.
Japan is unlikely to replace its existing supply model with a completely different one. The more realistic objective is to make the model less fragile through stockpiling, overseas investment, alternative procurement and more adaptable refineries.
Oil Will Decline Without Becoming Strategically Unimportant
Japan’s oil market is moving toward lower consumption and fewer refineries. That direction is supported by demographic change, transport electrification and national decarbonisation policy. It does not remove the need for petroleum security.
The country will continue importing almost all of its crude, and Middle Eastern suppliers will probably retain a dominant role because of their scale, reliability and established commercial relationships. The main policy question is how much concentration Japan can safely accept.
Strategic stocks, coastal refining, resilient distribution and overseas investment provide protection, but each has limits. Japan’s petroleum system will become smaller over time, yet it must remain capable of supplying essential transport and industry during both normal conditions and international crises. Managing that controlled reduction, without creating new import vulnerabilities, will define the future of oil in Japan.
