A curable composition comprising: a polymerization reaction product comprising a polyorganosiloxane having an aryl group bound to a silicon atom and an unsaturated aliphatic bond, and represented by an average compositional formula of the following Formula 4 or 5; particles satisfying the following Equation 1 in an amount from 0.1 to 30 parts by weight, relative to 100 parts by weight of the polyorganosiloxane; and a cross-linked polyorganosiloxane having an average compositional formula represented by the following Formula 13: [Formula 4] (R 11 3 SiO 1/2) 1 (R 11 2 SiO 2/2) m (R 11 SiO 3/2) n (SiO 4/2) o wherein R 11 's are each independently an epoxy group, a (meth)acryloyl group, an isocyanate group, or a monovalent hydrocarbon group, provided that at least one of R 11 's is an alkenyl group and that at least one of R 11 's is an aryl group; the sum (l+m+n+o) of l, m, n and o is 1, n is in a range of 0.01 to 0.30, and m/(m+n+o) is equal to or greater than 0.7 and less than 1; [Formula 5] (R 12 R 13 2 SiO 1/2) e (R 14 R 15 SiO 2/2) f (R 16 2 SiO 2/2) g (R 17 SiO 3/2) h wherein R 12 is a monovalent hydrocarbon group, R 13 is an alkyl group having 1 to 4 carbon atoms, R 14 is an alkyl group, an alkenyl group, or an aryl group, R 15 is an aryl group, R 16 is an alkyl group, R 17 is a monovalent hydrocarbon group, the sum (e+f+g+h) of e, f, g and h is 1, e is in a range of 0.01 to 0.15, f is in a range of 0 to 0.97, g is in a range of 0 to 0.97, h is in a range of 0.01 to 0.30, and (f+g)/(f+g+h) is equal to or greater than 0.7 and less than 1; A − B ≤ 0.1 wherein A represents a refractive index of the curable composition that does not comprise the particles or a cured product thereof, and B represents a refractive index of the particles; [Formula 13] (R 22 3 SiO 1/2) a (R 22 2 SiO 2/2) b (R 22 SiO 3/2) c (SiO 4/2) d wherein R 22 is each independently an epoxy group, a (meth)acryloyl group, an isocyanate group, or a monovalent hydrocarbon group, provided that at least one of R 22 is an alkenyl group, and that at least one of R 22 is an aryl group, the sum (a+b+c+d) of a, b, c and d is 1, a is in a range of 0 to 0.5, b is in a range of 0 to 0.3, c is in a range of 0.3 to 0.95, d is in a range of 0 to 0.2, and b/(b+c+d) is less than or equal to 0.3, and c/(c+d) is greater than or equal to 0.8. a polymerization reaction product comprising a polyorganosiloxane having an aryl group bound to a silicon atom and an unsaturated aliphatic bond, and represented by an average compositional formula of the following Formula 4 or 5; particles satisfying the following Equation 1 in an amount from 0.1 to 30 parts by weight, relative to 100 parts by weight of the polyorganosiloxane; and a cross-linked polyorganosiloxane having an average compositional formula represented by the following Formula 13: [Formula 4] (R 11 3 SiO 1/2) 1 (R 11 2 SiO 2/2) m (R 11 SiO 3/2) n (SiO 4/2) o wherein R 11 's are each independently an epoxy group, a (meth)acryloyl group, an isocyanate group, or a monovalent hydrocarbon group, provided that at least one of R 11 's is an alkenyl group and that at least one of R 11 's is an aryl group; the sum (l+m+n+o) of l, m, n and o is 1, n is in a range of 0.01 to 0.30, and m/(m+n+o) is equal to or greater than 0.7 and less than 1; [Formula 5] (R 12 R 13 2 SiO 1/2) e (R 14 R 15 SiO 2/2) f (R 16 2 SiO 2/2) g (R 17 SiO 3/2) h wherein R 12 is a monovalent hydrocarbon group, R 13 is an alkyl group having 1 to 4 carbon atoms, R 14 is an alkyl group, an alkenyl group, or an aryl group, R 15 is an aryl group, R 16 is an alkyl group, R 17 is a monovalent hydrocarbon group, the sum (e+f+g+h) of e, f, g and h is 1, e is in a range of 0.01 to 0.15, f is in a range of 0 to 0.97, g is in a range of 0 to 0.97, h is in a range of 0.01 to 0.30, and (f+g)/(f+g+h) is equal to or greater than 0.7 and less than 1; A − B ≤ 0.1 wherein A represents a refractive index of the curable composition that does not comprise the particles or a cured product thereof, and B represents a refractive index of the particles; [Formula 13] (R 22 3 SiO 1/2) a (R 22 2 SiO 2/2) b (R 22 SiO 3/2) c (SiO 4/2) d wherein R 22 is each independently an epoxy group, a (meth)acryloyl group, an isocyanate group, or a monovalent hydrocarbon group, provided that at least one of R 22 is an alkenyl group, and that at least one of R 22 is an aryl group, the sum (a+b+c+d) of a, b, c and d is 1, a is in a range of 0 to 0.5, b is in a range of 0 to 0.3, c is in a range of 0.3 to 0.95, d is in a range of 0 to 0.2, and b/(b+c+d) is less than or equal to 0.3, and c/(c+d) is greater than or equal to 0.8.