A sealing device comprises a first insert body and a second insert body. The first insert body has an annular first frame, and a first sealing part coupled to the first frame. The second insert body has an annular second frame having a diameter smaller than that of the first frame, and a second sealing part coupled to the second frame. The second insert body rotates relative to the first insert body. The first insert body and the second insert body are arranged such that a gap is formed between the first sealing part and the second sealing part. The second sealing part has a first surface facing the first sealing part and spaced apart from the second frame in a first axial direction; and a first baffle protruding toward the first sealing part from the end of the first surface in the outer radial direction thereof.