Abstract: A labyrinth (32) is provided in a gap (22) formed between a fixed-side end surface (13E) of a fixed-side housing and a rotation-side end surface (15C) of a rotation-side housing (15). The labyrinth (32) is constituted by a fixed-side recessed part (13F), a fixed-side fitting projecting part (13G), a rotation-side fitting projecting part (15D), and a rotation-side recessed part (15E). First and second fabric-like members (33), (34) formed annularly by a fabric-like material are provided in the fixed-side recessed part (13F) and the rotation-side recessed part (15E), respectively. A grease accommodating space (35) in which grease (G) is filled is provided between the first fabric-like member (33) and the second fabric-like member (34).