A ball bearing in which an annular cage with a plurality of pockets formed through the annular cage is incorporated between inner and outer rings, a ball is housed in each pocket, the annular cage is guided by the outer ring, and a relationship between a radial clearance (guide clearance) of the annular cage with respect to the outer ring and an axial clearance (pocket clearance) of an inner wall face of the pocket with respect to the ball is set at .