PURPOSE: To improve the storage stability in a state of a composition containing a vulcanizing agent and a vulcanization accelerator, by mixing a crosslinking group-containing elastomer with a polyepoxy compound vulcanizing agent, a (conjugated) base vulcanization accelerator and a triazinethiol stabilizer.

CONSTITUTION: A vulcanizable rubber composition excellent in storage stability is formed by mixing an elastomer (1) containing carboxyl groups as crosslinking groups with a polyepoxy compound vulcanizing agent (2) reactive with said crosslinking groups, a vulcanization accelerator (3) which is a base or a conjugat ed base having a base dissociation constant (Kb) in water at 25°C in the range of 10-1W103 and causing no crosslinking by reaction with the crosslinking groups of said elastomer and a triazinethiol stabilizer (4). The amount of said triazinethiol added is about 0.01W1pt.wt. per 100pts.wt. elastomer.