A dust seal is provided with a tubular fitting portion, a bush end surface abutting portion, a lip portion and a sealing projection integrally formed. The sealing projection is formed to project in an axially opposite direction to the lip portion from a radial inner section of the bush end surface abutting portion and abuts against a chamfered portion of a bush in such a manner as to overlap the chamfered portion. Therefore, at the time of supplying lubricant between the bush and a connecting pin, the sealing projection can prevent a part of the lubricant from entering between an end surface of the bush and the bush end surface abutting portion of the dust seal to maintain a sealed state therebetween. In consequence, the dust seal can be stably held on the inner peripheral side of a boss member, preventing the pulling-out of the dust seal.