A plasma processing apparatus for processing a substrate using plasma includes a first electrode configured to mount the substrate, a second electrode disposed to face the first electrode with a predetermined space, a chamber containing the first electrode and the second electrode, the chamber being capable of adjusting an inside atmosphere, a first electric power source device configured to apply a first RF voltage for controlling a self-bias voltage generated on the substrate to the first electrode, the first electric power source device applying a substantially constant width and a substantially constant value in a peak-to-peak voltage of an RF voltage of a first frequency at intervals, and a second electric power source device configured to apply a second RF voltage of a second frequency for generating plasma between the first and second electrodes to one of the first electrode and the second electrode.