A method of manufacturing a semiconductor device according to one embodiment includes forming a first film including a first metal above a processing target member. The method includes forming a second film including two or more types of element out of a second metal, carbon, and boron above the first film. The method includes forming a third film including the first metal above the second film. The method includes forming a mask film by providing an opening part to a stacked film including the first film, the second film and the third film. The method includes processing the processing target member by performing etching using the mask film as a mask.