A curable silicone composition comprising: an organopolysiloxane having at least two alkenyl groups in a molecule and represented by the following average unit formula: (R 1 R 2 2 SiO 1/2) a (R 3 2 SiO 2/2) b (R 4 SiO 3/2) c wherein, R 1 is an alkenyl group having from 2 to 12 carbons; R 2 are the same or different, and are each an alkyl group having from 1 to 12 carbons, an alkenyl group having from 2 to 12 carbons, an aryl group having from 6 to 20 carbons, or an aralkyl group having from 7 to 20 carbons; R 3 are the same or different, and are each an alkyl group having from 1 to 12 carbons, an alkenyl group having from 2 to 12 carbons, or a phenyl group; R 4 is an aryl group having from 6 to 20 carbons or an aralkyl group having from 7 to 20 carbons; and a, b, and c are numbers that satisfy the following conditions: 0.01 ≤ a ≤ 0.5, 0 ≤ b ≤ 0.7, 0.1 ≤ c < 0.9, and a + b + c =1; a straight chain organopolysiloxane having at least two alkenyl groups in a molecule and having no silicon-bonded hydrogen atoms, in an amount of 0 to 70% by mass of this composition; an organosiloxane (C 1) represented by the following general formula: HR 5 R 6 SiO(R 7 2 SiO) n SiR 5 R 6 H wherein, R 5 are the same or different, and are each an alkyl group having from 1 to 12 carbons; R 6 are the same or different, and are each an aryl group having from 6 to 20 carbons or an aralkyl group having from 7 to 20 carbons; R 7 are the same or different, and are each an alkyl group having from 1 to 12 carbons or a phenyl group; and n is a number from 0 to 100, an organopolysiloxane (C 2) having at least two silicon-bonded hydrogen atoms in a molecule and represented by the following average unit formula: (HR 5 R 6 SiO 1/2) d (HR 5 2 SiO 1/2) e (R 7 2 SiO 2/2) f (R 6 SiO 3/2) g wherein, R 5, R 6, and R 7 are synonymous with those described above; and d, e, f, and g are numbers that satisfy the following conditions: 0.01 ≤ d ≤ 0.7, 0 ≤ e ≤ 0.5, 0 ≤ f ≤ 0.7, 0.1 ≤ g < 0.9, and d + e + f + g =1, or a mixture of components (C 1) and (C 2), in an amount such that the number of silicon-bonded hydrogen atoms in this component is from 0.1 to 5 moles per 1 mol of total alkenyl groups in components and; and an effective quantity of a hydrosilylation reaction catalyst. an organopolysiloxane having at least two alkenyl groups in a molecule and represented by the following average unit formula: (R 1 R 2 2 SiO 1/2) a (R 3 2 SiO 2/2) b (R 4 SiO 3/2) c wherein, R 1 is an alkenyl group having from 2 to 12 carbons; R 2 are the same or different, and are each an alkyl group having from 1 to 12 carbons, an alkenyl group having from 2 to 12 carbons, an aryl group having from 6 to 20 carbons, or an aralkyl group having from 7 to 20 carbons; R 3 are the same or different, and are each an alkyl group having from 1 to 12 carbons, an alkenyl group having from 2 to 12 carbons, or a phenyl group; R 4 is an aryl group having from 6 to 20 carbons or an aralkyl group having from 7 to 20 carbons; and a, b, and c are numbers that satisfy the following conditions: 0.01 ≤ a ≤ 0.5, 0 ≤ b ≤ 0.7, 0.1 ≤ c < 0.9, and a + b + c =1; a straight chain organopolysiloxane having at least two alkenyl groups in a molecule and having no silicon-bonded hydrogen atoms, in an amount of 0 to 70% by mass of this composition; an organosiloxane (C 1) represented by the following general formula: HR 5 R 6 SiO(R 7 2 SiO) n SiR 5 R 6 H wherein, R 5 are the same or different, and are each an alkyl group having from 1 to 12 carbons; R 6 are the same or different, and are each an aryl group having from 6 to 20 carbons or an aralkyl group having from 7 to 20 carbons; R 7 are the same or different, and are each an alkyl group having from 1 to 12 carbons or a phenyl group; and n is a number from 0 to 100, an organopolysiloxane (C 2) having at least two silicon-bonded hydrogen atoms in a molecule and represented by the following average unit formula: (HR 5 R 6 SiO 1/2) d (HR 5 2 SiO 1/2) e (R 7 2 SiO 2/2) f (R 6 SiO 3/2) g wherein, R 5, R 6, and R 7 are synonymous with those described above; and d, e, f, and g are numbers that satisfy the following conditions: 0.01 ≤ d ≤ 0.7, 0 ≤ e ≤ 0.5, 0 ≤ f ≤ 0.7, 0.1 ≤ g < 0.9, and d + e + f + g =1, or a mixture of components (C 1) and (C 2), in an amount such that the number of silicon-bonded hydrogen atoms in this component is from 0.1 to 5 moles per 1 mol of total alkenyl groups in components and; and an effective quantity of a hydrosilylation reaction catalyst.