| May 1925 |
Establish to SAN-EI SHOTEN in Otaru-city Hokkaido as the dealer of the mining machinery |
| Apr 1935 |
Named SAN-EI@SHOTEN Co,.Ltd and establish as annex to SAN-EI SEIKI SEISAKUSHO for the manufacturer of the Air Motor, Air Winch, Rock drill. |
| Oct 1938 |
Move head office to Tokyo city, and start branch factory and branch office in Korea and North China. |
| Apr 1942 |
Designated by government as a munitions factory to produce Semi diesel Engine, Aircraft Parts etc. |
| Apr 1946 |
Designated by the Ministry of Commerce and Industry as a mining machinery manufacturer. |
| Oct 1954 |
Move head office to Otaru-city and start Tokyo office and Fukuoka branch. |
| Jun 1961 |
Established Fukushima factory in Kohri-cho Date-gun Fukushima to increase the production of the Air Motor. |
| Oct 1963 |
Start Osaka branch and renamed Fukushima factory as KOHRI SEIKI SEISAKUSHO Co.,Ltd. |
| Apr 1967 |
Start manufacturing of Hydraulic Motor. |
| Apr 1975 |
Rename SAN-EI SEIKI SEISAKUSHO Co.,Ltd. to OTARU SEISAKUSHO Co.,Ltd. and to produce the other field's goods. |
| May 1975 |
Rename KOHRI SEIKI SEISAKUSHO Co.,Ltd. to SAN-EI SEIKI SEISAKUHO Co.,Ltd. and succeed to manufacturing. |
| Jan 1976 |
Obtain the Permission of Crane and Hoist Manufacturing. |
| Dec 1978 |
Increase the capital to \20,000,000. |
| Jan 1984 |
Increase the equipment investment to \200,000,000. by purchasing the machining centers. |
| Feb 1989 |
Inaugurate Mrs. Etsuko Yamamoto as the president. |
| Mar 1992 |
Start manufacturing of Air Balancer. |
| Apr 1995 |
Restrict the organization to unite business section and production section. |
| May 1998 |
Increase the capital to \50,000,000. |
| Sep 1998 |
Move Tokyo office from Nihonbashi to Asakusabashi. |