Ōharu (大治町, Ōharu-chō) is a town located in Ama District, Aichi Prefecture, Japan.

The total area of the town is 6.59 square kilometres (2.54 sq mi).

Ōharu is located in western Aichi Prefecture, and has developed largely as a commuter town for the neighboring Nagoya metropolis.

Per Japanese census data,[2] the population of Ōharu has increased dramatically over the past 50 years.

In 2008, discussions were held to merge Ōharu with neighboring Shippō, Jimokuji and Miwa towns.