Masan is an administrative region located in the city of Changwon within South Gyeongsang Province, South Korea. It functioned as an independent city from 1949 until June 30, 2010, when it was merged into Changwon along with Jinhae.
Following its incorporation into Changwon, Masan was divided into two distinct districts: Masanhappo District and Masanhoewon District. As of December 31, 2012, the combined population of these two districts was 406,893.