A shower head includes a face plate having an outer peripheral portion and a plurality of gas injection holes disposed inside the outer peripheral portion, a movable portion facing the face plate and having a gas introduction passage, and a seal interposed between the outer peripheral portion of the face plate and the movable portion. The movable portion is arranged to move, in the first direction, between a first position in which the movable portion is coupled to the face plate by interposing the seal between the movable portion and the face plate, and the gas introduction passage communicates with the inside of the chamber via the gas injection holes, and a second position in which the movable portion is separated from the face plate, and the gas introduction passage communicates with the inside of the chamber via a gap between the movable portion and the face plate.