Multilayer core molding method

A multilayer core molding method for molding a multilayer core of a golf ball, the multilayer core molding method comprising:

• an upstream process of obtaining an intermediate molded body;
• and
• a downstream process of performing molding using a downstream process molding apparatus, wherein
• the intermediate molded body includes:
• an inner core;
• and
• an unvulcanized or semi-vulcanized first outer core material that covers only part of a surface of the inner core and is integrated with the inner core, and
• the downstream process molding apparatus includes:
• a first downstream process mold including a substantially hemispherical first downstream process mold cavity surface;
• a second downstream process mold including a substantially hemispherical second downstream process mold cavity surface;
• and
• an intermediate plate including a substantially hemispherical intermediate plate cavity surface configured to be arranged facing the first downstream process mold cavity surface, and wherein
• the downstream process includes:
• an intermediate molded body arrangement step of arranging the intermediate molded body on the intermediate plate cavity surface or the first downstream process mold cavity surface;
• and
• a first vulcanization step, performed after the intermediate molded body arrangement step, of vulcanization-molding the intermediate molded body until the intermediate molded body is substantially or completely vulcanized, in a state in which at least the first downstream process mold and the intermediate plate are closed against each other.