Water-absorbing rubber composition

A water-absorbing rubber composition comprising (A) a 1,3-diene rubber with a crystal or glass region content of 5-50% when measured at about 25.degree. C. having molecular weight of 50,000 to 1,000,000 and a melting point of the crystal regions of 20.degree.-90.degree. C., and (B) a highly water-absorbing resin dispersed in said rubber, the ratio of mixing said 1,3-diene rubber to said water-absorbing resin ranging from 10-300 parts by weight of resin per 100 parts by weight of said rubber, said resin being a product of crosslinking of a polymer which contains as a monomer at least 40 mole percent of an .alpha.,.beta.-unsaturated compound containing 1 or 2 groups each selected from the class consisting of a carboxyl group and a group convertible to a carboxyl group with at least one crosslinking agent selected from the group consisting of a polyfunctional epoxy compound containing at least two epoxy groups and a polyamine having a molecular weight or 60-5000 and represented by a general formula H--(NH--CH.sub.2 --CH.sub.2 --).sub.n NH.sub.2 wherein n is an integer of 1 to 110, said resin being in the form of a powder capable of passing through a 20-mesh Tyler screen and absorbing 20-500 times its own weight of distilled water.