Abstract: An adhesive sheet is provided having an expandable adhesive layer having a foaming agent and excellent thermal conductivity after foaming curing. The adhesive sheet comprises a substrate, a first adhesive layer disposed on one surface of the substrate, and a second adhesive layer disposed on the other side of the substrate. The first adhesive layer comprises an adhesive (A), a thermally conductive filler (B) having a mean short side length of 1 ?m or more, and a foaming agent (C). The thermally conductive filler (B) has an aspect ratio of 1.3 or more and includes a filler (B-1). The second adhesive layer contains an adhesive (A?), a thermally conductive filler (B?) having a mean short side length of 1 ?m or more, and a foaming agent (C?). The thermally conductive filler (B?) p comprises a filler (B?-1) having an aspect ratio of 1.3 or more.