A plasma processing apparatus includes a plasma generation chamber in which plasma active species are generated, a process chamber configured to accommodate processing target objects stacked in a vertical direction, the plasma active species generated in the plasma generation chamber being supplied into the process chamber, a plasma source gas supply pipe disposed inside the plasma generation chamber and extending in the vertical direction, a plasma source gas being introduced from one end of the plasma source gas supply pipe and discharged through gas discharge holes formed in the plasma source gas supply pipe in the vertical direction, and a pair of plasma electrodes, arranged to face each other, configured to apply an electric field to the plasma source gas discharged into the plasma generation chamber. A size of a discharge area interposed between the pair of plasma electrodes is varied in the vertical direction.