The invention provides a rubber composition for golf balls which includes (A) a base rubber containing a polybutadiene having a cis-1,4 bond content of at least 60 wt %, (B) an unsaturated carboxylic acid and/or a metal salt thereof, and (C) a benzimidazole of general formula (1) below wherein R1 and R2 are each independently a hydrogen atom or a hydrocarbon group of 1 to 20 carbons, and m and n are each an integer from 1 to 4, with the proviso that if m and/or n is 2 or more, each occurrence of R1 and R2 may be the same or different. The golf ball rubber composition of the invention enables a high-quality molded and crosslinked product having a suitable hardness and a high resilience to be obtained.