A silicone composition that contains (A) an organopolysiloxane having at least two aliphatic unsaturated hydrocarbon groups per molecule, (B) a filler containing an aluminum powder and a zinc oxide powder, (C) an organohydrogenpolysiloxane having two or more silicon-bonded hydrogen atoms per molecule, and (D) a platinum group metal catalyst, in which a cured product of the silicone composition exhibits a ratio of a storage elastic modulus after 3,600 seconds from the start of measurement to a storage elastic modulus after 7,200 seconds from the start of measurement of 0.7 or less, the storage elastic modulus G′ being measured by constructing a program for holding a sample at 150° C. for 7,200 seconds after the sample is heated from 25° C. to 125° C. at a temperature increase rate of 10° C./min, from 125° C. to 145° C. at a temperature increase rate of 2° C./min, and from 145° C. to 150° C. at a temperature increase rate of 0.5° C./min.