Changan (Korean: 장강군, 長江郡) is a county in Chagang Province, North Korea. The county town is Changan.
Until 1949, the county was part of the city of Kange. Changgang borders the city of Gangge and the counties of Sijun in the west, Songan in the south, Chason in the north, Hwapyeong and Nannim in the east.

The terrain is mountainous. There are the Gangnamsan Mountains in the northeast and the Choguryeongsan Mountains in the southwest. The highest point is Mount Geumphasan (금파산, 1918 m) at the northern border of the county.

The county in the southeast is connected to the city of Kange by a railway. There are food and pharmaceutical industries, zinc deposits are being developed. Rice and other grains are grown on the banks of the Cheongsong (종성강) River, and grapes are cultivated in the mountains.