A golf ball 2 has a spherical core 4 and a cover 6 positioned outside this core 4. The core 4 has a spherical center 8 and a mid layer 10 positioned outside this center 8. The center 8 is formed by crosslinking a rubber composition. A base rubber of the rubber composition contains polybutadiene as a principal component. The rubber composition contains sulfur as a crosslinking agent. The center 8 has a diameter of 1 mm or greater and 15 mm or less. The center 8 has a central hardness H1 of 20 or greater and 50 or less. A difference (H4−H3) between a hardness H4 of a surface of the mid layer 10 and a hardness of an innermost part thereof is equal to or greater than 10.