| 1960 | Established SuncoHatsujo Co., Ltd. in Tsunashima-Higashi, Kohoku-ku, Yokohama City, Kanagawa Prefecture. |
|---|---|
| 1973 | Expansion of 2nd and 3rd plants |
| 1998 | Company name changed to Sunco Spring Co., Ltd. from SuncoHatsujo Co., Ltd. |
| 2002 | Expansion of 4th and 5th plants |
| 2011 | 50th Anniversary |
| 2011 | Became a wholly owned subsidiary of Kyokuto Boeki Kaisha, LTD. |
| 2013 | Establishment of a new research institute |
| 2014 | Establishment of Osaka office |
