Ōchi (相知町 Ōchi-chō?) was a town located in the Higashimatsuura District of Saga Prefecture, Japan. As such it had its own town hall. Ōchi was founded as Ōchi-mura (Ōchi-village) by the amalgamation of 16 smaller villages in 1889. It became Ōchi-town (Ōchi-chō) in 1935.
As of 2003, the town had an estimated population of 8,890 and a density of 136.60 persons per km². The total area was 65.08 km².
On January 1, 2005, Ōchi, along with the towns of Chinzei, Hamatama, Hizen, Kyūragi and Yobuko, and the village of Kitahata (all from Higashimatsuura District), was merged into the expanded city of Karatsu. The old town hall became the Ōchi branch office of Karatsu City Hall.
The main train station, Ōchi Station (), is on the Karatsu Line of Kyushu Railway Company (JR Kyushu) running from Nishi-Karatsu Station in Karatsu to Kubota Station in Saga. A smaller line, part of the Chikuhi Line, runs from Yamamoto Station of Karatsu City, through Nishi-Ōchi Station (West-Ōchi) to Imari Station in Imari City, a notable pottery centre in Saga Prefecture, along with Karatsu and Arita. The next station south from Nishi-Ōchi is Sari Station.