Provided are a heat-conductive silicone composition having good heat dissipation characteristics, and a semiconductor device using the said composition. A heat-conductive silicone composition containing: (A) an organopolysiloxane expressed by average composition formula (1): Formula (1): R1aSiO(4-a)/2 (In the formula, R1 represents a hydrogen atom, a C1-18 saturated or unsaturated univalent hydrocarbon group, or a hydroxy group, and a satisfies the expression 1.8 ≤ a ≤ 2.2), the organopolysiloxane having kinetic viscosity at 25°C of 10-100,000 mm2/s; (B) silver powder having a tapped density of 3.0 g/cm3 or more, a specific surface area of 2.0 m2/g or less, and an aspect ratio of 1-30; (C) elemental gallium and/or a gallium alloy having a melting point of 0-70°C, the mass ratio [component (C)/{component (B) + component (C)}] being 0.001-0.1; and (D) a catalyst selected from the group consisting of platinum catalysts, organic peroxides, and condensation reaction catalysts.