Chain

A chain (11) includes the following: a pair of inner link plates (12) which face each other; a cylindrical bush (17); a pin (20) that passes through the bush (17); a pair of outer link plates (14); and seal parts (19). The bush (17) passes through a first insertion hole (16) of each of the inner link plates (12), and both end parts of the bush protrude to the outside of the pair of inner link plates (12). The pair of outer link plates (14) are disposed so as to sandwich the pair of inner link plates (12) from the outside. Both end parts of the pin (20) pass through a second insertion hole (21) of each of the outer link plates (14). Each seal part (19) is disposed between one of the inner link plates (12) and one of the outer link plates (14) so as to surround the pin (20). Each seal part (19) is provided with: a seal base (30); a second elastic ring (36); a third elastic ring (39); and a bristle part (41). Between the seal base (30) and the inner link plate (12), the second elastic ring (36) is disposed so as