To provide a golf ball producing method capable of enhancing uniformity.

An uncrosslinked polymer composition 45 is inserted into a half shell molding die 17 having a half shell shape cavity 33, so as to mold the half shell 47. Then a center part is covered by a pair of half shells 47, so as to mold a preliminary molded body. The preliminary molded body is crosslinked and molded by a core molding die, then the core is produced. When the capacity of the cavity 33 is defined as V1, and the volume of the polymer composition 45 is defined as V2, the ratio V2/V1 is ≥ 90% and ≤ 100%. When the half shells 47 are used, a polymer flowability is improved in the case of molding the preliminary molded body and crosslinking/ molding the core. Consequently, the core uniform in the cover layer being the intermediate layer of the golf ball is obtained. The golf ball using the core is excellent in the uniformity of performance.