Ŭiju is a kun, or county, in North Pyongan Province, North Korea. The county has an area of 420 km², and a population of 110,018 (2008 data).

Ŭiju appears as Uiju in South Korea's Revised Romanization and as Yizhou in Chinese sources, as during its occupation by general Mao Wenlong's forces during the Transition from Ming to Qing.

Ŭiju County borders Sakchu county and Kusŏng to the east, Sŏnch'ŏn and Ch'ŏlsan counties to the south, and Ryongch'ŏn county and Sinŭiju to the west, respectively. To the north, Ŭiju shares a border with China.

Ŭiju county is divided into 1 ŭp (town), 2 rodongjagu (workers' districts) and 17 ri (villages):

Ŭiju county is served by the Tŏkhyŏn Line of the Korean State Railway. There is also an airport, Uiju Airfield (ICAO airport code: ZKUJ).

Ŭiju earthquake was a 5.3 magnitude earthquake that occurred in Ŭiju County in 1980. It is among the largest earthquakes by magnitude recorded in the Korean Peninsula since South Korea began official earthquake observation in 1978.

40°11′49″N 124°31′55″E / 40.19694°N 124.53194°E / 40.19694; 124.53194