A plasma processing method for processing a substrate with plasma by applying a high frequency to a reaction chamber, and applying a second high frequency to a substrate holder includes covering at least 90% of a total surface area of an inner wall of the reaction chamber that is directly exposed to plasma with a dielectric, disposing a DC earth comprising a conductive portion that is earthed and having an area less than 10% of the inner wall of the reaction chamber, and performing plasma processing to the substrate in the reaction chamber having the DC earth located at a position where a floating potential of plasma is higher than the floating potential of plasma at the inner wall of the reaction chamber that is closest to the substrate.