A substrate processing method includes (a) forming a recess on a workpiece by partially etching the workpiece; and (b) forming a film having a thickness that differs along a depth direction of the recess, on a side wall of the recess. Step (b) includes (b-1) supplying a first reactant, and causing the first reactant to be adsorbed to the side wall of the recess; and (b-2) supplying a second reactant, and causing the second reactant to react with the first reactant thereby forming a film.