A raw material supply device (105) includes an introduction pipe (152a) which introduces a carrier gas into a raw material vessel (151), a transport pipe (152b) which transports a source gas fed out from the raw material vessel, a supply pipe (155a) which is branched from the transport pipe and supplies the source gas to a film forming chamber (101), a circulation pipe (155b) which is branched from the transport pipe (152b) and returns the source gas to the introduction pipe (152a), an introduction valve (156a) which is attached to the introduction pipe, a supply valve (156b) which is attached to the supply pipe, a circulation valve (156c) which is attached to the circulation pipe, and a controller (157) which controls opening/closing of the valves. The controller controls the supply valve and the circulation valve to be in opposite open/closed states. The source gas can be supplied more stably while suppressing the waste of the raw material.