A golf ball 2 includes a core 4, a mid layer 6, a reinforcing layer 8, and a cover 10. When distances (%) from the central point of the core 4 to nine points and JIS-C hardnesses at the nine points, which are obtained by dividing a region from the central point of the core 4 to the surface of the core 4 at intervals of 12.5% of the radius of the core 4, are plotted in a graph, R2 of a linear approximation curve obtained by a least-square method is equal to or greater than 0.95. The difference (H(100)-H(0)) between a JIS-C hardness H(100) at the surface of the core 4 and a JIS-C hardness H(0) at the central point of the core 4 is equal to or greater than 15.