A heat dissipation component for a semiconductor element includes: a composite part containing 50-80 vol % diamond powder with the remainder having metal including aluminum, the diamond powder having a particle diameter volume distribution first peak at 5-25 μm and a second peak at 55-195 μm. A ratio between a volume distribution area at particle diameters of 1-35 μm and a volume distribution area at particle diameters of 45-205 μm is 1:9 to 4:6; surface layers on both composite part principal surfaces, each of the surface layers containing 80 vol % or more metal including aluminum and having a film thickness of 0.03-0.2 mm; and a crystalline Ni layer and an Au layer on at least one of the surface layers, the crystalline Ni layer having a film thickness of 0.5-6.5 μm, and the Au layer having a film thickness of 0.05 μm or larger.