In September 1949, the company began manufacturing carrier telephone equipment in Gotanda, Shinagawa Ward, Tokyo, and was established in January 1950 as Oi Electric Co., Ltd. In May 1960, the company moved its base of operations to its current location in Kikuna, Kohoku Ward, Yokohama City, Kanagawa Prefecture, where it has continued to expand and renovate ever since.

The Mizusawa Factory, the predecessor of Mizusawa Works, was established in January 1967 as the production division of Oi Electric, after being designated as an invited factory with the support of Iwate Prefecture and Mizusawa City (now Oshu City). In November 1973, the factory was built and relocated to its current location, and has since grown steadily. On October 1, 1989, it merged with Oi Electric to become Mizusawa Works, and restarted as Oi Electric's production base. By introducing various equipment, the factory strives to further improve manufacturing quality, and is constantly innovating, such as improving technology and building efficient production lines. A wide variety of products, including mobile communication devices and industrial information and communication devices, are produced at Mizusawa Works.

It was established in April 1990 as a development base for our products and technologies. We mainly develop mobile communication devices, digital communication devices, and information and communication systems. In order to keep up with the rapid advances in communication technology and develop new technologies, we are creating an environment where young engineers can concentrate on the development themes and research they are passionate about.