A plasma processing method for generating plasma in a vacuum chamber and processing a substrate placed on a substrate electrode, the plasma being generated by supplying a high-frequency power having a frequency of 50 MHz to 3 GHz to an antenna provided opposite to the substrate electrode while interior of the vacuum chamber is controlled to a specified pressure by supplying a gas into the vacuum chamber and exhausting the interior of the vacuum chamber, the method includes with a dielectric plate being sandwiched between the antenna and the vacuum chamber and both the antenna and the dielectric plate projecting into the vacuum chamber, controlling plasma distribution on the substrate with an annular and recessed slit provided between the antenna and the vacuum chamber, and processing the substrate in a state where the antenna cover is fixed by making both an inner side face of the slit and the antenna covered with an antenna cover, making a bottom face of the slit covered with a slit cover, supporting the antenna cover by the slit cover, and fixing the slit cover to a wall surface of the vacuum chamber.