A method of manufacturing a semiconductor device includes the steps of loading a substrate into a processing chamber; processing the substrate by supplying plural kinds of reaction substances into the processing chamber multiple number of times; and unloading the processed substrate from the processing chamber, wherein at least one of the plural kinds of reaction substances contains a source gas obtained by vaporizing a liquid source by a vaporizing part; in the step of processing the substrate, vaporizing operation of supplying the liquid source to the vaporizing part and vaporizing the liquid source is intermittently performed, and at least at a time other than performing the vaporizing operation of the liquid source, a solvent capable of dissolving the liquid source is flowed to the vaporizing part at a first flow rate; and at a time other than performing the vaporizing operation of the liquid source and every time performing the vaporizing operation of the liquid source prescribed number of times, the solvent is flowed to the vaporizing part at a second flow rate larger than the first flow rate.