The crystalline semiconductor film is formed following steps that supplying a film formation gas to a second gas diffusion area from a gas introduction port provided in an upper electrode; supplying the film formation gas to a first gas diffusion area from the second gas diffusion area through holes provided in a dispersion plate between the first gas diffusion area and the second gas diffusion area; supplying the film formation gas into a treatment room from the first gas diffusion area through holes in a shower plate between the first gas diffusion area and the treatment room; generating glow discharge plasma by supplying high frequency electricity from an electrode surface of the upper electrode; generating crystal nuclei on a substrate provided over a lower electrode facing the upper electrode; and growing the crystal nuclei. A portion of the dispersion plate which faces the gas introduction port has no hole.