Abstract: An object of the present invention is to provide a novel golf ball having excellent spin performance on approach shots. The present invention provides a golf ball comprising a golf ball body and a paint film composed of at least one layer and formed on a surface of the golf ball body, wherein a base resin constituting an outermost layer of the paint film is a polyurethane obtained by a reaction between (A) a polyol composition and (B) a polyisocyanate composition, and a loss modulus (E?) at the temperature of ?50° C. obtained by measuring a dynamic viscoelasticity of the polyurethane is 1.00×108 Pa or more.

Abstract: In a head, a center vertical cross section passing through a face center satisfies the following (a) and (b): (a) when a boundary point between an inner surface of a crown portion and an inner surface of a face portion is defined as a CF inner surface boundary point, a curvature radius of a head inner surface at the CF inner surface boundary point is 6.0 mm or greater and 10.0 mm or less, and the head thickness at the CF inner surface boundary point is 2.0 mm or greater; and (b) when a spot located 10 mm apart from the CF inner surface boundary point toward the crown side is defined as a spot C10, the head thickness reduces gradually from the CF inner surface boundary point to the spot C10, and the head thickness at the spot C10 is 1.0 mm or less.

Abstract: In a head, a center vertical cross section passing through a face center satisfies the following (a) and (b): (a) when a boundary point between an inner surface of a crown portion and an inner surface of a face portion is defined as a CF inner surface boundary point, a curvature radius of a head inner surface at the CF inner surface boundary point is 6.0 mm or greater and 10.0 mm or less, and the head thickness at the CF inner surface boundary point is 2.0 mm or greater; and (b) when a spot located 10 mm apart from the CF inner surface boundary point toward the crown side is defined as a spot C10, the head thickness reduces gradually from the CF inner surface boundary point to the spot C10, and the head thickness at the spot C10 is 1.0 mm or less.

Abstract: An object of the present invention is to provide a novel golf ball having excellent spin performance on approach shots. The present invention provides a golf ball comprising a golf ball body and a paint film composed of at least one layer and formed on a surface of the golf ball body, wherein a base resin constituting an outermost layer of the paint film is a polyurethane obtained by a reaction between (A) a polyol composition and (B) a polyisocyanate composition, and a loss modulus (E?) at the temperature of ?50° C. obtained by measuring a dynamic viscoelasticity of the polyurethane is 1.00×108 Pa or more.

Abstract: A golf club set includes a plurality of golf clubs 1 having different loft angles. The golf clubs 1 include at least one 1st golf club 1A having a loft angle of less than 34 degrees, and at least one 2nd golf club 1B having a loft angle of not less than 34 degrees. Each of the at least one 1st golf club 1A and the at least one 2nd golf club 1B comprises a clubface 3 provided with a plurality of face grooves 8 having a depth. The depth of the face grooves 8 of the at least one 2nd golf club 1B is larger than the depth of the face grooves 8 of the at least one 1st golf club 1A.

Abstract: A golf club set includes at least one first golf club whose loft angle is not less than 46 degrees and less than 56 degrees, and at least one second golf club whose loft angle is not less than 56 degrees and less than 60 degrees. The first and second golf clubs each comprise a face provided with score lines each formed by a groove having a groove bottom and a pair of opposite grooves walls which are inclined at an inclination angle with respect to a normal direction to the face so that the groove width between the opposite grooves walls is increased from the groove bottom toward the face. The inclination angle of the groove walls of the score lines of the first golf club is in the range from 28 to 42 degrees. The inclination angle of the groove walls of the score lines of the second golf club is in the range from 23 to 37 degrees and smaller than that of the first golf club.

Abstract: A golf club set includes a plurality of golf clubs 1 having different loft angles. The golf clubs 1 include at least one 1st golf club 1A having a loft angle of less than 34 degrees, and at least one 2nd golf club 1B having a loft angle of not less than 34 degrees. Each of the at least one 1st golf club 1A and the at least one 2nd golf club 1B comprises a clubface 3 provided with a plurality of face grooves 8 having a depth. The depth of the face grooves 8 of the at least one 2nd golf club 1B is larger than the depth of the face grooves 8 of the at least one 1st golf club 1A.

Abstract: A golf club set includes at least one first golf club whose loft angle is not less than 46 degrees and less than 56 degrees, and at least one second golf club whose loft angle is not less than 56 degrees and less than 60 degrees. The first and second golf clubs each comprise a face provided with score lines each formed by a groove having a groove bottom and a pair of opposite grooves walls which are inclined at an inclination angle with respect to a normal direction to the face so that the groove width between the opposite grooves walls is increased from the groove bottom toward the face. The inclination angle of the groove walls of the score lines of the first golf club is in the range from 28 to 42 degrees. The inclination angle of the groove walls of the score lines of the second golf club is in the range from 23 to 37 degrees and smaller than that of the first golf club.

Abstract: Provided is a fitting apparatus that accurately and objectively determines an optimal swingability index, which is a swingability index of a golf club suited to a golfer. The fitting apparatus is provided with an acquisition unit, a calculation unit, and a determination unit. The acquisition unit acquires a measurement value obtained by measuring a swing action of a test club by the golfer with a measurement device. The calculation unit calculates a swing index indicating a feature amount of the swing action, based on the measurement value. The determination unit determines the optimal swingability index, according to a magnitude of the swing index.

Abstract: A head 2 includes a face surface 4, a back surface 6, and a sole surface 8. The back surface 6 includes a top side region Rt and a sole side region Rs. The sole side region Rs includes a sole side inclination surface Sb1 inclined to increase a face thickness toward a sole side, a plurality of back recessed parts Rb1 formed on the sole side inclination surface Sb1, and a wall WL1 formed between the back recessed parts Rb1 adjacent to each other. A low specific gravity member X1 having a specific gravity lower than the specific gravity of the face material is disposed on at least one of the back recessed parts Rb1. The head 2 has a loft angle of equal to or greater than 42°. The head 2 has a sweet spot height of equal to or greater than 19 mm.

Abstract: Provided is a fitting apparatus that accurately and objectively determines an optimal swingability index, which is a swingability index of a golf club suited to a golfer. The fitting apparatus is provided with an acquisition unit, a calculation unit, and a determination unit. The acquisition unit acquires a measurement value obtained by measuring a swing action of a test club by the golfer with a measurement device. The calculation unit calculates a swing index indicating a feature amount of the swing action, based on the measurement value. The determination unit determines the optimal swingability index, according to a magnitude of the swing index.