Karatsu (唐津市; -shi) is a city located in Saga, Japan.
As of 2003, the city has an estimated population of 78,713 and the density of 617.41 persons per km². The total area is 127.49 km².
The city was founded on January 1, 1932.
Karatsu's is famous for its Karatsu Kunchi festival, which runs annually from November 2nd to November 4th and is visited by approximately 500,000 visitors. The festival consists primarily of hikiyama (floats) being carried around the city's narrow streets to cheers of "Enya! Enya" from the spectators.