[Problem] To provide a rotating classifier which can keep classification performance high and which can prevent blockages caused by biomass and the like.[Means for Resolution] The rotating classifier is characterized in that: comb teeth-like protrusion portions protruding toward a fixed member side are provided on top of rotary classification fins at intervals along the circumferential direction of the rotating classifier fins; a first gap is provided between an upper end portion of each of the comb teeth-like protrusion portions and a lower surface of the fixed member; a second gap formed between a protrusion portion and a protrusion portion adjacent to the protrusion portion is connected to the first gap; and an air stream flowing from the radial outside to the radial inside of the comb teeth-like protrusion portions through the first gap and the second gap is formed due to the rotation of the rotary classification fins.