PURPOSE: A method for cleaning a process chamber is provided to efficiently remove a thin film including aluminum and transition metal attached to the inner wall of a process chamber by generating byproducts with boron-nitrogen elements. CONSTITUTION: A thin film is removed by supplying cleaning gas including the first gas with boron and the second gas with fluorine to a process chamber. The inner temperature of the process chamber is raised to a cleaning temperature(s01). The inner side of the process chamber is exhausted with purge and vacuum states(s02). A thin film is removed by supplying first to third gas(s03). The inside of the process chamber is purged(s04).
