Isawa village was created on April 1, 1955 through the merger of the villages of Oyama, Natsuta and Wakayanagi. It was raised to town status on April 1, 1967. On February 20, 2006, Isawa, was merged with the cities of Esashi and Mizusawa, the town of Maesawa, and the village of Koromogawa (both from Isawa District), was merged to create the city of Ōshū, and no longer exists as an independent municipality.
As of February 2006, the town had an estimated population of 17,297 and a population density of 58.04 persons per km². The total area was 298.02 km².