A sealing device in accordance with the present invention includes a projected portion having a rubber-like elastic member on the outer periphery of a seal member, and an outer cylindrical portion extending toward the seal member on a flange portion of a sleeve member. This outer cylindrical portion covers an opening formed between the seal member and the flange portion, thereby preventing entry of dust. The outer cylindrical portion is further provided on the tip thereof with a bend portion which can be engaged with the projected portion. The projected portion, the outer cylindrical portion, and the bend portion form a small clearance which serves as a labyrinth seal. The projected portion is fixedly fitted with a protection ring for covering the opening formed between the seal member and the flange portion of the sleeve member so that the free end portion of the protection ring can be engaged with the flange. This free end portion of the protection ring and the flange portion form a small clearance, and this small clearance serves as a labyrinth seal.