| 1984-02 |
50th anniversary of establishment |
| 1985-04 |
Opened Shizuoka Plant in Yoshida-cho, Haibara-gun |
| 1985-10 |
Okamoto Riken Rubber Co., Ltd. changed its trade name to Okamoto Industries, Inc. |
| 1989-07 |
Teamed with Michelin to establish the joint venture Michelin Okamoto Tire Corporation |
| 1998-04 |
Established subsidiary SIAM OKAMOTO Co., Ltd. in Thailand |
| 1999-08 |
Established subsidiary APOLLOTEX Co., Ltd. in Thailand |
| 2000-03 |
Dissolved business association with Michelin, transferred joint venture |
| 2000-04 |
Acquired Hillson-Dec Co., Ltd. as a subsidiary |
| 2001-03 |
Acquired Union Royal Co., Ltd. as a subsidiary |
| 2002-08 |
Acquired laminate film business |
| 2004-04 |
Acquired dehumidifier ("Mizutori-zosan") business |
| 2004-05 |
Established subsidiary OKAMOTO RUBBER PRODUCTS Co., Ltd. in Thailand |
| 2004-08 |
Established subsidiary OKAMOTO VIETNAM Co., Ltd. in Vietnam |
| 2004-09 |
Acquired Secaicho Co., Ltd. as a subsidiary |
| 2004-12 |
Acquired decorative films business |
| 2005-03 |
Acquired Ichijiku Pharmaceutical Co., Ltd. as a subsidiary |
| 2005-06 |
Acquired laminate film ("allomer film") business |
| 2006-03 |
Acquired cockroach insecticide ("INPYRETH") business |
| 2006-08 |
Opened Joso Distribution Center in Joso-shi, Ibaraki Prefecture |
| 2006-11 |
Established subsidiary Okamoto Industries (Shenzhen) Co., Ltd. in China |
| 2007-04 |
Acquired dehydrant/absorbent sheet for food products ("Pichitto") business via transfer |
| 2007-05 |
Established subsidiary VINA OKAMOTO Co., Ltd. in Vietnam |
| 2007-07 |
Established subsidiary OKAMOTO SANDUSKY Manufacturing L.L.C. in USA |
| 2009-11 |
Opened Ushiku Distribution Center in Ushiku-shi, Ibaraki Prefecture |
| 2010-10 |
Secaicho Co., Ltd. and Union Royal Co., Ltd. merged to become Secaicho Union Corporation |
| 2012-01 |
Opened Okayama Distribution Center in Nagi-cho, Katsuta-gun, Okayama Prefecture |
| 2012-04 |
Acquired Funabori Rubber Co., Ltd. as a subsidiary |
| 2013-02 |
Established subsidiary Okamoto Manufacturing（GD）Ltd. in China |
| 2013-06 |
Okamoto Sewing Co., Ltd. changed its trade name to Shoe Tech Okamoto Co., Ltd. |
| 2013-10 |
Commenced business of solar power generation for selling power |
| 2014-02 |
創業80周年 |
| 2017-09 |
理研コランダム株式会社を子会社化 |
| 2017-09 |
Acquired Riken Corundum Co., Ltd. as a subsidiary |
| 2018-03 |
つくば工場（茨城県牛久市）開設 |
| 2019-02 |
創業85周年 |
| 2019-02 |
85th anniversary of establishment |
| 2020-10 |
オカモト環境開発（株）の設立 |
| 2024-02 |
創業90周年 |
