An object of the present invention is to provide a heat-expandable/peelable acrylic pressure-sensitive adhesive tape that maintains a high adhesion force, and can be easily separated or debonded at the bonded part by heating, regardless of the material constituting the adherend.Disclosed is a heat-expandable/peelable acrylic pressure-sensitive adhesive tape or sheet which includes at least a pressure-sensitive adhesive layer containing a blowing agent, a peelable or peel-assisting film layer, and a viscoelastic substrate containing microparticles, in which at least the peelable or peel-assisting film layer and the microparticle-containing viscoelastic substrate constitute a multilayer structure, and the multilayer structure is arranged on or above at least one side of the pressure-sensitive adhesive layer so that the blowing agent-containing pressure-sensitive adhesive layer is in contact with the peelable or peel-assisting film layer with or without the interposition of another layer.