Resin-made ball bearing retainer and ball bearing

A resin cage for a ball bearing, the resin cage comprising:

• at least one circular ring portion;
• and
• a plurality of column portions extending in an axial direction from the circular ring portion, wherein
• balls of a ball bearing are rotatably holdable by cylindrical or partially cylindrical pockets formed between the column portions adjacent to each other, and the circular ring portion has a guide surface guided by an inner circumferential surface of an outer ring or an outer circumferential surface of an inner ring of the ball bearing,
• a roundness of the guide surface is 5 μm or less,
• differences between angles formed by centers of the pockets adjacent to each other and 360°/number of pockets are all within ±0.1°, and
• orientations of centers of all the pockets are oriented toward one side in a circumferential direction and one side in the axial direction from an outer diameter side toward an inner diameter side.