STEP 1 (Pressure increasing step) increases pressure within a raw material container to first pressure by supplying carrier gas to the inside of the raw material container by PCV. STEP 2 (Pressure decreasing step) decreases the pressure within the raw material container to second pressure by operating an exhaust device and discarding the raw material gas from a raw material gas supply pipe via an exhaust bypass pipe. STEP 3 (Stabilization step) stabilizes the vaporization efficiency for vaporizing the raw material inside the raw material container by operating the exhaust device and discarding the raw material gas while introducing the carrier gas into the raw material container. STEP 4 (Film forming step) supplies the raw material gas to the inside of the processing container via the raw material gas supply pipe and deposits a thin film on a wafer by CVD.