A ball retainer for a slide apparatus and a mold for manufacturing the same. The ball retainer includes, in a width direction, a first extension part and a second extension part that are extended from a center line, forming a pre-determined angle with each other, in a length direction, a body part formed in the center, and a pair of holding parts. Each holding part is respectively formed at each end of the body part. Each holding part includes a plurality of ball insertion grooves for inserting balls that are spaced apart in the length direction. Expansion parts each having an expanding cross-sectional area are respectively formed at both sides in the length direction of the first extension part and the second extension part.