龟城市（朝鲜语：구성시）是朝鲜民主主义人民共和国平安北道的一个市，位于该道中南部。面积666.8平方公里。

朝鲜王朝时期设郡。1967年建市。

Kusŏng is a city in central North Pyongan province, North Korea. It borders Taegwan to the north, Taechon to the east, Kwaksan and Chongju to the south, and Chonma to the north. The highest point is Chongryongsan (청룡산, 920 m). The year-round average temperature is 8.2 °C, with a January average of -9.6 °C and an August average of 23.3 °C. 1300 millimeters of rain fall in a typical year. 22% of the county's area is cultivated; 64% is forested.