A golf ball comprising a spherical core having an inner core and an outer core , and a cover positioned outside the spherical core , wherein the inner core is spherical and has a diameter of 16 mm or more and 24 mm or less, and wherein A×a is 12,200 or less, and B×b is 20,400 or more, where "a" represents an average Shore C hardness of a hardness (H2.5) at a point of 2.5 mm from a center of the spherical core and a hardness (H5) at a point of 5 mm from the center of the spherical core , "b" represents an average Shore C hardness of a hardness (H7.5) at a point of 7.5 mm from the center of the spherical core and a hardness (H9) at a point of 9 mm from the center of the spherical core , "A" represents an impulse difference in kN·μs between a back spin impulse and a top spin impulse measured using a contact force tester under a condition corresponding to a condition when the golf ball is hit with a driver, and "B" represents an impulse difference in kN·μs between a back spin impulse and a top spin impulse measured using a contact force tester under a condition corresponding to a condition when the golf ball is hit with an 8-iron, wherein the average Shore C hardness "a" and "b" and the impulse difference "A" and "B" are determined by the respective evaluation methods 2, 6 and 7 defined in the examples of the description. wherein the inner core is spherical and has a diameter of 16 mm or more and 24 mm or less, and wherein A×a is 12,200 or less, and B×b is 20,400 or more, where "a" represents an average Shore C hardness of a hardness (H2.5) at a point of 2.5 mm from a center of the spherical core and a hardness (H5) at a point of 5 mm from the center of the spherical core , "b" represents an average Shore C hardness of a hardness (H7.5) at a point of 7.5 mm from the center of the spherical core and a hardness (H9) at a point of 9 mm from the center of the spherical core , "A" represents an impulse difference in kN·μs between a back spin impulse and a top spin impulse measured using a contact force tester under a condition corresponding to a condition when the golf ball is hit with a driver, and "B" represents an impulse difference in kN·μs between a back spin impulse and a top spin impulse measured using a contact force tester under a condition corresponding to a condition when the golf ball is hit with an 8-iron, A×a is 12,200 or less, and B×b is 20,400 or more, where "a" represents an average Shore C hardness of a hardness (H2.5) at a point of 2.5 mm from a center of the spherical core and a hardness (H5) at a point of 5 mm from the center of the spherical core , "b" represents an average Shore C hardness of a hardness (H7.5) at a point of 7.5 mm from the center of the spherical core and a hardness (H9) at a point of 9 mm from the center of the spherical core , "A" represents an impulse difference in kN·μs between a back spin impulse and a top spin impulse measured using a contact force tester under a condition corresponding to a condition when the golf ball is hit with a driver, and "B" represents an impulse difference in kN·μs between a back spin impulse and a top spin impulse measured using a contact force tester under a condition corresponding to a condition when the golf ball is hit with an 8-iron, wherein the average Shore C hardness "a" and "b" and the impulse difference "A" and "B" are determined by the respective evaluation methods 2, 6 and 7 defined in the examples of the description. <EOS>