Ogi (小城市, Ogi-shi) is a city located in the central part of Saga Prefecture on the island of Kyushu, Japan.

At the inner part of Suminoe Bay at the mouth of the Rokkaku River, the tidal range is the largest in Japan, reaching a maximum of about 6 meters during spring tides.

Saga Prefecture Ogi has a humid subtropical climate (Köppen Cfa) characterized by warm summers and cool winters with light to no snowfall.

Following the Meiji restoration, the town of Ogi and villages of Ashikari, Haruta, Iwamatsu, Mikazuki, Misato, Togawa and Ushizu were established with the creation of the modern municipalities system of April 1, 1889.

In terms of national politics, the city is part of the Saga 2nd district of the lower house of the Diet of Japan.