A compounding agent for rubber vulcanization containing an amino alcohol salt of a carboxylic acid group-containing disulfide, obtained by a reaction of a dithiocarboxylic acid and an amino alcohol, having the formula (I): wherein R1 and R2 are, independently, hydrogen or a C1 to C20 organic group which may have a hetero atom and/or a substituent group, R1 and R2 may bond together to form a ring, X indicates a C1 to C20 organic group which may have a hetero atom and/or a substituent group, n and m are integers of 0, 1 or 2 and n+m is 1 to 4 whereby an improvement of the vulcanization speed and vulcanized rubber properties, without having a detrimental effect on the scorch time, its production method, a rubber composition including, the same, and a rubber composition for metal bonding containing (A) 100 parts by weight of a diene-based rubber (B) 0.05 to 10 parts by weight of an amino alcohol salt compound of a carboxylic acid group-containing disulfide having the formula (I) and (C) 0.05 to 5 parts by weight of an organic metal salt, as metal content, improved in bonding performance with metal and low heat buildup property.