A golf ball having, as a constituent element, an article molded under heat from a rubber composition which includes: (a) a base rubber containing polybutadiene having a stress relaxation time (T80), defined as the time in seconds from the moment when rotor rotation is stopped immediately after measurement of the ML1+4 (100° C.) value (the Mooney viscosity measured at 100° C. in accordance with ASTM D-1646-96) that is required for the ML1+4 value to decrease 80%, of at most 3.5, (b) an unsaturated carboxylic acid and/or a metal salt thereof, and (c) an organic peroxide. The golf ball has an excellent rebound.