There is provided a plasma processing apparatus that can generate uniform plasma without increasing costs per unit electric power even though the discharge area is increased to adapt to samples in given sizes by arranging a plurality of plasma discharge units. A plasma processing apparatus includes an RF power supply having an RF signal circuit and an RF power circuit, a case, and a discharge electrode. A plasma module is configured of the discharge electrode and the RF power circuit provided in the case. A frequency signal from the RF signal circuit is inputted to a plurality of the plasma modules connected in parallel with each other.