PURPOSE: To provide a lot of useful characteristics such as strong adhesion of rubber materials consisting of two or more rubber compsn. regardless of co-vulcanization properties among them and existence of vulcanization of the rubber materials, prevention of compounded ingredients in the rubber materials from diffusion and migration after adhesion and no obstruction of flexibility caused by the adhesion.

CONSTITUTION: Rubber materials consisting of at least two unvulcanized or vulcanized rubber compsn. wherein the same or different rubber ingredients having critical surface tensions γc in specified ranges are incorporated are combined and an ultrahigh mol.wt. polyethylene sheet made by means of scraping method is sandwiched between these rubber materials and after these are laminated, they are vulcanized or heated at a temp. being m.p. of the polyethylene sheet or higher to fuse and integrate them.