A plasma processing device and method which allow control of a density ratio between ions and radicals, including a processing chamber, a radio frequency power supply which supplies microwave radio frequency power for plasma generation, a magnetic field generating mechanism which generates a magnetic field in the processing chamber, a sample stand disposed in the processing chamber, and a shielding plate disposed above the sample stand for shielding incidence of an ions onto the sample stand. The magnetic field generating mechanism includes a coil disposed around an outer periphery of the processing chamber, and a power supply connected to the coil. The mechanism allows a power supply of the magnetic field generating mechanism or the radio frequency power supply to control a plasma generating position with respect to the shielding plate, and to generate plasma by periodically changing the plasma generating position vertically with respect to the shielding plate.