A surface processing device and method for forming a magnetic field having a uniform strength over a wide area of an electrode surface to generate a uniform high density plasma over the overall surface of a wafer. The device comprises a vacuum container contains a first electrode and a second electrode disposed opposite to the first electrode; a gas feeding system for feeding a predetermined gas into the vacuum container; an evacuating system for maintaining the inside of the container at a reduced pressure; an electric field generating system for generating an electric field in a region between the first and second electrodes; and a magnetic field generating system for generating a magnetic field in the vacuum container. The magnetic field generating system comprising a plurality of magnets arranged around the outer periphery of the container so as to form a ring in such a manner that directions of magnetization thereof differ from adjacent magnetic element making a 720 degree rotation along the circumference of said ring.