To correctly mold a cover with a uniform thickness without an eccentricity by providing plural core support pins which are arranged in an area except the equator and the boeh poles of a spherical cavity in a golf ball injection molding mold to be freely movable forward and backward to the substantial center of the cavity.

A metallic mold 1 is provided with a hollow and spherical cavity 2 which is formed from an upper mold 1a and a lower mold 1b and a parting line P is formed in the equator correspondence position of the cavity 2. Further, two semi-ring-shaped runners 14 and 14 communicating with an injection molding machine are formed at positions which surround the equator of the cavity 2 in the metallic mold 1 and injection gates 5 are provided along the peripheral direction in the inner peripheral part of the respective runners 14 through plural nozzle-shaped runner parts 11. In this case, plural pairs of core support pins 13 being freely movable forward and backward to the center of the cavity 2 are formed in the area near angles α=45° against a division surface P and a core arranged inside the cavity 2 is supported at the center position.