Masan is an administrative region of Changwon, a city of South Gyeongsang Province, South Korea. It was formerly an independent city from 1949 until 30 June 2010, when it was absorbed to Changwon along with Jinhae. Masan was redistricted as two districts within Changwon, Masanhappo District and Masanhoewon District. On 31 December 2012, the population of the districts combined was 406,893.