A rubber composition for a golf ball having excellent rebound characteristics and excellent durability, and showing good workability, which contains a base rubber, a co-crosslinking agent, an organic peroxide and an inorganic filler, wherein the base rubber includes a polybutadiene containing a cis-1,4 bond of not less than 80%, having a Mooney viscosity of not less than 30 to less than 50 ML.sub.1+4(100.degree. C.) and a ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of 3.0 to 6.0, synthesized using a lanthanide-containing catalyst.