The 1905 South Australian state election was held on 27 May 1905. All 42 seats in the South Australian House of Assembly were up for election. The incumbent conservative government led by Premier of South Australia Richard Butler in an informal coalition with the liberals was defeated by the United Labor Party (ULP) led by Leader of the Opposition Thomas Price. Each of the 13 districts elected multiple members, with voters casting multiple votes.

The premier of South Australia is the head of government in the state of South Australia, Australia. The Government of South Australia follows the Westminster system, with a Parliament of South Australia acting as the legislature. The premier is appointed by the governor of South Australia, and by modern convention holds office by virtue of their ability to command the support of a majority of members of the lower house of Parliament, the House of Assembly.