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 a plasma) can efficiently be suppressed and controlled in order to manufacture stable products. An apparatus includes a processing chamber, a surrounding member disposed around the processing chamber, an RF induction coil disposed outside the dielectric member, and an air-core coil for generating a direct-current magnetic field supplied to the inner space. The surrounding member seals an opening on top of the processing chamber to create an inner space, and the RF induction coil is above the top surface of the surrounding member.