A plasma processing apparatus capable of, over a prolonged period of time, controlling a decrease in the value of a DC current flowing within an accommodating compartment. The plasma processing apparatus comprises an accommodating compartment adapted to accommodate a substrate and perform a plasma treatment thereon, a high-frequency power source adapted to supply high-frequency power to the inside of the accommodating compartment; a DC electrode adapted to apply a DC voltage to the inside of the accommodating compartment, a ground electrode provided within the accommodating compartment and used for the applied DC voltage, and an exhaust unit adapted to evacuate the inside of the accommodating compartment.