An adhesive composition-supporting separator for a battery includes a porous substrate supporting thereon a thermally cross-linkable adhesive composition comprising a multi-functional isocyanate and a reactive polymer having a functional group capable of reacting with an isocyanato group of the multi-functional isocyanate; an electrode/separator laminate is obtained by contact pressing the adhesive composition-supporting separator for a battery against electrodes; and an electrode/separator bonded material having a cross-linked adhesive composition is obtained by heating the electrode/separator laminate to thereby react the multifunctional isocyanate with the reactive polymer for causing cross-linking.