A bush bearing includes a bearing body having an inner peripheral surface which is brought into contact with a cylindrical outer peripheral surface of a rotating shaft portion so as to be rotatable in a first direction, a groove provided on an outer peripheral surface of the bearing body so as to extend in the first direction, and an elastic ring fitted on said groove and having a pair of projecting portions and a portion, the pair of projecting portions partially projecting radially outward from the outer peripheral surface of said bearing body in second direction, the portion being provided at positions in the first direction between the pair of projecting portions, and not projecting radially outward from the outer peripheral surface of the bearing body.