A plasma technique in which a plasma generation technique frequently used in various fields including a semiconductor manufacturing process is used, and generation of plasma instability (high-speed impedance change of plasma) can efficiently be suppressed and controlled in order to manufacture stable products. An apparatus includes a processing chamber, a surrounding member disposed so as to surround the processing chamber, an RF induction coil disposed above the top surface, a direct-current magnetic field generator for supplying a direct-current magnetic field to the inner space, and an RF cut filter connected to a direct current (DC) power supply and connected to the direct-current magnetic field generator. The RF cut filter includes a first capacitor connected to a positive terminal of the DC power supply and to ground, and a second capacitor connected to a negative terminal of the DC power supply and to ground.