Provided are an adhesion removal method capable of removing sulfur-containing adhesions that adhere onto the inner surface of a chamber or the inner surface of a pipe connected to the chamber without disassembly of the chamber and a film-forming method. Sulfur-containing adhesions adhering onto at least one of the inner surface of a chamber (10) and the inner surface of a discharge pipe (15) connected to the chamber (10) are removed by reaction with a cleaning gas containing an oxygen-containing compound gas.