Provided is a plasma processing method capable of improving an etching selectivity of a material to be etched with respect to a mask material and reducing a roughness of a side wall of a mask pattern. The plasma processing method of selectively depositing a deposition film on the mask material with respect to the material to be etched includes controlling an etching parameter so that an incubation time of the mask material is shorter than an incubation time of the material to be etched.