A ball bearing retainer holds balls disposed between an inner ring and an outer ring, in pockets formed at a plurality of portions, in a circumferential direction, of an annular body. The annular body includes: annular parts disposed on both sides in an axial direction; and pillar parts that are disposed at a plurality of portions in the circumferential direction and that connect between the annular parts. The pockets are formed by the annular parts and the pillar parts adjacent to each other in the circumferential direction, and allow ball guide. First contact portions of the pillar portions, which contact portions contact with the balls in the circumferential direction, are formed by first planes that extend along the axial direction, and the balls are guided by the first planes.