A substrate processing method of embedding a silicon nitride film in a recess formed in a surface of a substrate, includes repeating a cycle, the cycle including: a first operation of supplying a silicon precursor to form an adsorption layer of the silicon precursor on the substrate; a second operation of supplying a first nitrogen-containing gas and supplying a first power to an upper electrode to generate a first plasma, and exposing the substrate to the first plasma to nitride the adsorption layer and form the silicon nitride film; and a third operation of supplying a second nitrogen-containing gas and supplying a second power to a lower electrode to generate a second plasma different from the first plasma, and exposing the substrate to the second plasma to modify an upper portion of the recess and form an adsorption-inhibiting area.