PURPOSE: To provide an O/W emulsion type adhesive for rubber which contains a reduced amt. of an org. solvent, makes removal of water easy and has almost the same level of resistance to fatigue breakdown after vulcanization as a conventional solvent type adhesive, prepd. by adding specified components to rubber.

CONSTITUTION: The adhesive is prepd. by emulsifying a mixt. of 100pts.wt. (A) rubber selected from among natural rubber, polybutadiene rubber, styrene/butadiene rubber, etc., 30pts.wt. or higher (B) carbon black having an iodine absorption of 40mg/g or higher, 0.5pts.wt. or higher (C) zinc compd. having a zinc content of 0.5pts.wt. or higher (e.g. zinc stearate), 3W30pts.wt. (D) tackifier having an average M.W. of 1,000W10,000 (e.g. coumarone indene resin), (E) an org. solvent having a boiling point of below 150°C (e.g. benzene) and (F) a nonionic emulsifier having an HLB value of 2W8 (e.g. sorbitan stearate), in water which is used in an amt. at least three times as much as the total volume of the above six components.