A golf ball includes a core and a cover. The core is formed of a material molded under heat from a rubber composition. The rubber composition includes components (A) through (C). The components (A) through (C) are (A) a base rubber, (B) an organic peroxide, and (C) a water providing agent. The water providing agent releases water at a vulcanization temperature at which the rubber composition is vulcanized. The dissociation rate of water of the water providing agent in the case of heating the water providing agent up to the vulcanization temperature of the rubber composition is 60% by mass or more.