Ōkuchi (大口市, Ōkuchi-shi) was a city located in Kagoshima Prefecture, Japan.

Part of the southern border of the city is the Sendai River and the artificial lake formed from the Tsuruta dam.

At one time, Ōkuchi was a prosperous city but has declined for several reasons in recent years.

First, there has been a decline in forestry and agriculture in the area, but the aging Japanese population and the flight to larger cities have also been significant factors.

Shin-Minamata Station on the Kyushu Shinkansen is 35 km northwest (operated by Kyushu Railway Company) Kagoshima Airport in Kirishima (35 km SSE of Ōkuchi) Ōkuchi has two sister cities: