The present application discloses a retainer and a bearing. The retainer includes a first ring and a second ring, as well as multiple beams connecting the first ring and the second ring. The multiple beams are spaced apart from each other in a circumferential direction of the retainer and a pocket for accommodating a rolling element of a bearing is defined between adjacent beams. The side surface of the beam in the circumferential direction includes a first pressure slope and a second pressure slope spaced apart from each other, and a recessed surface provided at one or two ends of the pocket of the retainer and extending from the first pressure slope towards a longitudinal centerline of the beam and towards a longitudinal end of the beam. The retainer facilitates bearing assembling, avoids the use of large instruments during the assembling, and reduces damage to various components of the bearing during the assembling.