Ansan is a city in Gyeonggi Province, South Korea. It lies south of Seoul, and is part of the Seoul National Capital Area.
Ansan is located 30 km south of Seoul and it is the home of ERICA (Education Research Industry Cluster @ Ansan) of Hanyang University. It is connected to Seoul by rail via Seoul Subway Line 4.
Ansan is situated on the coast of the Yellow Sea (locally called West Sea), at 37°19′N 126°50′E. Portions of various Yellow Sea islands lie within its jurisdiction. The largest and best-known of these is Daebu Island.
Several institutions of higher learning are located in Ansan. They include Ansan College, Ansan College of Technology, Seoul Institute of the Arts, and a campus of Hanyang University.
The Korea Transportation Safety Authority, a government agency of South Korea, is headquartered in Ansan.