The invention provides a method for thermally releasing an adherend, which comprises selectively releasing one or some of a plurality of substances adhered on a thermally releasable pressure-sensitive adhesive sheet having a thermally expandable layer containing therein thermo-expandable microspheres, by partly heating the pressure-sensitive adhesive sheet using a heating unit capable of partly heating the pressure-sensitive adhesive sheet. This thermally releasing method may further involve a step of cutting the substance adhered to the pressure-sensitive adhesive sheet. In this occasion, the heating unit has a heating portion of a shape in conformity with the shape of the adherend to be released, and may be provided on at lease one of the side to which the adherend is adhered and the opposite side thereto of the pressure-sensitive adhesive sheet.