The present invention provides a resin composition for golf balls that is excellent in resilience, flexibility, and fluidity. The present invention also provides a golf ball excellent in resilience, shot feeling, and productivity. The present invention includes a resin composition for golf balls including: (A) at least one selected from the group consisting of (a-1) a bipolymer of an olefin and a C3-C8 α,β-unsaturated carboxylic acid, (a-2) a metal ion-neutralized product of a bipolymer of an olefin and a C3-C8 α,β-unsaturated carboxylic acid, (a-3) a terpolymer of an olefin, a C3-C8 α,β-unsaturated carboxylic acid, and an α,β-unsaturated carboxylic acid ester, and (a-4) a metal ion-neutralized product of a terpolymer of an olefin, a C3-C8 α,β-unsaturated carboxylic acid, and an α,β-unsaturated carboxylic acid ester; (B) a compound containing an unsaturated hydrocarbon chain, a cationic moiety, and an anionic moiety in its molecule; and (C) an unsaturated fatty acid.