To provide a separable angular contact ball bearing and a combined angular contact ball bearing embodied at low cost, assuring a low dust generation, durability, long lifetime, and a high maintenance performance.

The separable angular contact ball bearing 1 is structured so that a retainer 7 to retain a plurality of rolling elements 6 in such a way as able to roll is installed between an outer ring 2 and an inner ring 3, wherein the outer 2 and inner rings 3 have respective grooves on one side, i.e. one stretch of circumferential groove 10 in the outer ring is formed at the internal circumferential surface of the outer ring 2 while one stretch of circumferential groove 13 in the inner ring is formed at the peripheral surface of the inner ring 3, and the retainer 7 is formed from a resin material approximately in an annular shape, and the peripheral surface and internal surface of the retainer 7 on its one side are provided with circumferentially stretching projections 21 which enable movement in the groove stretching direction while they are fitted in the outer ring groove 10 or the inner ring groove 13.