To bond even lowly moisture-permeable adherends tightly to each other by applying an emulsion adhesive to the bonding surface of either of the adherends before bonding them to each other with a moisture-curing adhesive based on a urethane prepolymer.

In a process for bonding adherends to each other with a moisture-curing adhesive based on an NCO-terminated urethane prepolymer obtained by reacting a polyol with a polyisocyanate, an emulsion adhesive or an emulsion primer is applied to the bonding surface of at least either of the adherends before they are bonded to each other with the adhesive, the adhesive is applied to at least either bonding surface while the adhesive or the primer remains in a tack-free state, and the adherends are bonded to each other by heating at 40°C or above.