A seal member 14 which seals a gap among a rotating body 9 provided in an opening of a frame body 13, a blade 18a, and the frame body 13 in an end region in an axial direction of the rotating body 9, the seal member 14 including: a first seal portion 14b which comes into contact with the rotating body 9; a second seal portion 14e which comes into contact with the blade 18a; and a third seal portion 14f which is constituted by a surface formed in a stair shape and sequentially arranged between the first seal portion 14b and the second seal portion 14e and which is capable of reducing a gap formed between the rotating body 9 and the blade 18a due to rotation of the rotating body 9.