PURPOSE: To provide a plasma surface processing device such that the self-bias voltage can be controlled suppressing fluctuation of a plasma condition.

CONSTITUTION: This plasma surface processing device is provided with a vacuum container 1 for processing the surface of a substrate 3 to be processed by a plasma, a lower part electrode 2 provided inside this vacuum container 1 for loading a substrate 3 to be processed, the high-frequency power supply 5 for controlling the potential of this lower part electrode 2 and a dipole ring magnet 8 for producing a magnetic field inside the vacuum container 1 and controlling the angle formed by magnetic line of force incident on the surface of the substrate 3 to be processed and the surface of the substrate 3 to be processed.