A seal member includes an annular fitting part and an annular dust lip. The fitting part fits on an inner circumference of a tubular member. The dust lip extends from the fitting part toward a side opposite from the tubular member such that a diameter of an inner circumference of the dust lip gradually decreases, and a distal end portion of the dust lip slides on an outer circumferential surface of a shaft member. A metal insert includes a reinforcing ring and a reinforcing extension piece. The reinforcing ring stands along the inner circumference of the tubular member. The reinforcing extension piece extends from the reinforcing ring toward a side opposite from the tubular member, and inclines such that a distal end of the reinforcing extension piece approaches the shaft member. The reinforcing ring is arranged in the fitting part, whereas the reinforcing extension piece is arranged in the dust lip.