| 1955 |
Japan Petroleum Exploration Co., Ltd. (JAPEX) was founded in 1955 as a company responsible for oil and natural gas exploration, development, and production. |
| 1955-12 |
Founded as a special company under the Japan Petroleum Resources Development Law |
| 1956-07 |
Discovery of the Hiyoridake Oil Field in Hokkaido, Japan's first domestic oil field (Production period 1956–1961) |
| 1958-07 |
Discovery of the Shinkawa Oil Field in Akita Prefecture (Production started in 1959, still in operation) |
| 1965-05 |
Expansion of business scope overseas due to amendments to the Japan Petroleum Resources Development Law |
| 1967-10 |
Integration into the Japan Petroleum Development Corporation upon its establishment |
| 1970-04 |
Separation from the Japan Petroleum Development Corporation and re-establishment as a private company |
| 1971-05 |
Establishment of Japan Marine Oil & Gas Development Co., Ltd. (JPO) |
| 1972-03 |
Discovery of the Niigata-Aga Offshore Oil & Gas Field, the first offshore oil field after JPO's establishment (Production period 1976–1998) |
| 1983-06 |
Discovery of the Niigata Iwafune Offshore Oil & Gas Field (Production started in 1990, ongoing) |
| 1996-03 |
Opening of the Niigata-Sendai Gas Pipeline |
| 2000-03 |
Initiation of LNG rail tank container transportation in Japan |
| 2003-01 |
Start of bitumen production in the Canada Oil Sands Project (ended in 2021) |
| 2003-12 |
Listing of shares on the First Section of the Tokyo Stock Exchange |
| 2007-05 |
Participation in the Kangean Project in Indonesia (ended in 2025) |
| 2011-11 |
Operation commencement of the Yufutsu LNG Receiving Terminal |
| 2012-08 |
Participation in the U.S. Tight Oil Development Business |
| 2013-04 |
Participation in the Canada Shale Gas Project (ended in 2021) |
| 2013-08 |
Start of crude oil production at the Gharraf Project in Iraq |
| 2014-06 |
Start of Megasolar operation at the Hokkaido Office |
| 2014-10 |
Participation in the Seagull Project in the North Sea, UK (ended in 2025) |
| 2018-03 |
Operation start of the Soma LNG Base |
| 2020-04 |
Commercial operation start of the Fukushima Natural Gas Power Plant |
| 2022-04 |
Change of listing market on the Tokyo Stock Exchange (to Prime Market) |
| 2022-10 |
Operation start of Abashiri Biomass Power Plant Unit 2 (and Unit 3 in March 2023) |
| 2023-05 |
Participation in exploration and development in Norwegian offshore mining blocks |
| 2024-06 |
Participation in the Freeport LNG Project in the U.S. |
| 2024-08 |
Operation start of Ozu Biomass Power Plant |
| 2024-12 |
Operation start of Chofu Biomass Power Plant |
| 2025-04 |
Operation start of Tahara Biomass Power Plant |
| 2025-08 |
Operation start of JAPEX Mihama Energy Storage Facility |
| 2025-10 |
Participation in exploration and development of the Gubang Mining Block in Indonesia |
| 2026-02 |
Participation in U.S. Tight Oil & Gas Development (Operator) |
