Nakatsu (中津市, Nakatsu-shi) is a city on the northern border of Ōita Prefecture in Kyushu, Japan.

Nakatsu is in the northwest corner of Ōita Prefecture, Kyushu and faces the Gulf of Suō on the Seto Inland Sea to the northeast.

Some 80% of the city area is mountainous, mainly in the south There is a wide stretch of flat, agricultural land which begins at the mouth of Yamakuni River and extends to Mount Hiko called the Nakatsu plain, making it the largest agricultural area in the prefecture.

After the Meiji restoration, the town of Nakatsu within Shimoge District, Ōita was established on May 1, 1889 with the creation of the modern municipalities system.

Nakatsu has a mayor-council form of government with a directly elected mayor and a unicameral city council of 24 members.

In terms of national politics, the city is part of the Ōita 3rd district of the lower house of the Diet of Japan.

JR Kyushu - Nippō Main Line The Nakatsu Gion Festival (中津祇園) is held every year in July.