Polyurethane elastomer foams can be prepared by mixing an isocyanate-terminated prepolymer obtained by reaction of a polyol with 3,3′-dimethylbiphenyl-4,4′-diisocyanate, with a foaming agent comprising a mixture of water, a low-molecular weight glycol having a molecular weight of 48-200, and a high-molecular weight glycol having a number average molecular weight Mn of 1000-3000 under stirring to conduct foaming reaction. The polyurethane elastomer foams so produced can have a high durability, particularly under a high load, even though a low-cost, easy-to-handle diisocyanate compound is used.