Patent ID: 8574097

Claim:
A golf ball comprising a core and a cover positioned outside the core, wherein the core includes a center and an envelope layer positioned outside the center, the center has a spherical space and an outer layer, the center has an inner diameter of 2 mm or greater and 13 mm or less, the center has an outer diameter of 5 mm or greater and 15 mm or less, the center has a JIS-C hardness H2, at its surface, of 25 or greater and 55 or less, a difference (H4−H3) between a JIS-C hardness H4 of the core at its surface and a JIS-C hardness H3 of the envelope layer at its innermost portion is equal to or greater than 10, the cover has a flexural modulus of 300 MPa or greater and 1000 MPa or less, and the cover has a tensile modulus of 400 MPa or greater and 1500 MPa or less.