Tosa (土佐市, Tosa-shi?) is a city located in Kōchi Prefecture, Japan. It is located on the southern coast of the island of Shikoku. The city was founded on January 1, 1959.
As of December 1, 2011, the city has an estimated population of 28,897, with 12,080 households and a population density of 315.50 persons per km². The total area is 91.59 km².
The city of Tosa should not be confused with the historical Tosa Province, which covered all of modern-day Kōchi Prefecture.
Tosa is located in central Kōchi Prefecture, and faces the Shikoku Mountain Range to the north and Pacific Ocean to the south. The Niyodo River flows through the Takaoka Plain in the town, where rice is grown.