A method for manufacturing a semiconductor device including a substrate to be processed having a conductive layer essentially consisting of platinum includes etching the conductive layer, and generating plasma and cleaning the substrate, to which an etching product adhere, by means of ions in the plasma. The cleaning includes heating the substrate to a first temperature, introducing gas, which contains chlorine and nitrogen and in which a ratio of chlorine atoms to nitrogen atoms is 9:1 to 5:5, and applying high-frequency power to an electrode, on which the substrate is placed.