Japanese subsidiary of Seiko Group Corporation, historically a key manufacturer of watch movements branded SII and TMI, now focused on precision technology after transferring watch business to Seiko Watch Corporation in 2020.
Founded in 1937 as Daini Seikosha Co., Ltd. (Second Seikosha) in Tokyo as a spin-off from Seikosha's watch division to handle Seiko timepiece manufacturing. Post-WWII, the company evolved and expanded into precision components, leveraging watchmaking expertise for semiconductors, micromechatronics, machine tools, and printers. In 2009, it became a wholly-owned subsidiary of Seiko Holdings via merger. SII produced mechanical and quartz watch movements labeled with the SII trademark, often used interchangeably with Seiko due to shared ownership. These movements were the same as those branded under TMI (Time Module Inc.), a former Hong Kong-based subsidiary that merged with SII. On April 1, 2020, SII transferred its watch business, including subsidiaries like Morioka Seiko Instruments and Ninohe Tokei Kogyo, to Seiko Watch Corporation, ending direct SII watch production. SII now focuses on non-watch products like crystal oscillators, thermal printers, and high-precision machine tools derived from watchmaking technology.
MOVEMENT TYPES
MANUFACTURING
Full ManufactureSPECIALIZATIONS
HEADQUARTERS
Chiba, Japan1937 Seiko Group (as Daini Seikosha)
2009 Seiko Holdings Corporation
2020 Seiko Group Corporation
