It is an object to reduce a chemical treating width in a peripheral edge part of a substrate while suppressing deterioration in each of uniformity of the chemical treating width and processing efficiency. In order to achieve the object, a substrate processing device for carrying out a chemical treatment for a substrate using a processing liquid having a reaction rate increased with a rise in temperature includes a substrate holding portion, a rotating portion for rotating the substrate held in the substrate holding portion in a substantially horizontal plane, a heating portion for injecting heating steam to a central part of a lower surface of the substrate to entirely heat the substrate, and a peripheral edge processing portion for supplying the processing liquid from above to a peripheral edge part of the substrate heated by the heating portion, thereby carrying out a chemical treatment for the peripheral edge part.