To provide a heat dissipation plate for a semiconductor device, which is high in heat conductivity and excellent in heat dissipation.

The heat dissipation plate for a semiconductor device includes an aluminum nitride sintered compact which contains 0.14 to 1.5 mass% of a Y element, a ratio (IAl₂Y₄O₉/IAlN) of 0.002 to 0.06 of an X-ray diffraction intensity IAl₂Y₄O₉ of an Al₂Y₄O₉ (201 plane) to an X-ray diffraction intensity IAlN of an aluminum nitride (101 plane), a ratio (IY₂O₃/IAlN) of 0.008 to 0.06 of an X-ray diffraction intensity IY₂O₃ of a Y₂O₃ (222 plane) to the X-ray diffraction intensity IAlN of the aluminum nitride (101 plane), a heat conductivity of ≥240 W/m-K, and a three-point bending strength of ≥200 MPa.