The present invention provides a
solid golf ball comprising a hot-molded product of a rubber composition comprising (a) 100 parts by weight of a
polybutadiene synthesized using a rare-earth catalyst and having a cis-1,4 content of at least 60% and a 1,2 vinyl content of at most 2%, having a
viscosity η at 25° C. as a 5 wt % solution in
toluene of up to 600 mPa·s, and having
Mooney viscosity (ML1+4 (100° C.)) of more than 30, (b) 0.01 to 0.5 parts by weight of a
sulfur, (c) 10 to 60 parts by weight of an unsaturated
carboxylic acid and / or a
metal salt thereof, (d) 0.1 to 5 parts by weight of an organosulfur compound, (e) 5 to 80 parts by weight of an
inorganic filler, and (f) 0.1 to 5 parts by weight of an
organic peroxide, wherein the hot-molded product has a difference in JIS-C
hardness between the center and surface thereof of more than 20 and up to 40. The
solid golf balls of the invention have a soft feel upon
impact and excellent rebound characteristics. Moreover, the
solid golf balls are improved in flight performance by making its spin rate reduced when shot with a driver.