A substrate processing method includes a substrate holding step of horizontally holding a substrate, a liquid film forming step of supplying a processing liquid onto the upper surface of the substrate to form a liquid film of the processing liquid covering the upper surface of the substrate, a liquid film-removed region-forming step of partially eliminating the processing liquid from the liquid film of the processing liquid to form a liquid film-removed region in the liquid film of the processing liquid, a liquid film-removed region enlarging step of enlarging the liquid film-removed region toward the outer periphery of the substrate, and a hydrogen fluoride atmosphere-holding step of keeping the ambient atmosphere at the boundary between the liquid film-removed region and the liquid film of the processing liquid as an atmosphere of hydrogen fluoride-containing vapor, in parallel with the liquid film-removed region enlarging step.