The substrate processing method is a substrate processing method for removing a resist having a hardened layer from a substrate on a surface of which the resist is formed, including: a substrate holding step of holding the substrate; and a resist stripping step of stripping the resist from the surface of the substrate by supplying ozone gas and superheated steam to a plural-fluid nozzle for producing liquid drops through mixing a plurality of fluids to discharge mixed gas of ozone gas and superheated steam containing liquid drops of ozone water produced by mixing ozone gas and superheated steam from the plural-fluid nozzle toward the surface of the substrate.