A solid golf ball comprising a core and a cover, wherein the core has a trans structure content in polybutadiene of 10 to 30%. The core is produced by vulcanizing a rubber composition containing a butadiene rubber having cis structure content of not less than 90% before vulcanization, as a base rubber, wherein an amount of trans structure after vulcanization is 10 to 30% and a difference in hardness measured by a JIS-C type hardness tester between the center of the core and each point located from the center to the surface at an interval of 5 mm is not more than 10%. The rubber composition for forming the core comprises a vulcanizing agent, a filler, an organic peroxide and an organophosphorus compound, in addition to the butadiene rubber having cis structure content of not less than 90% before vulcanization.