Seo District () is a gu, or district, in south-west central Busan, South Korea.
Seo-gu is divided into 8 legal dong, which altogether comprise 14 administrative dong, as follows:
In 1998 Ami 1-dong and Ami 2-dong were merged. In 2003 Seodaesin 2-dong and Seodaesin 1-dong were merged.
The district contains the island Dudo.
The area is represented in the National Assembly by the West District and East District Busan (South Korean Legislature Constituency)