A curable organopolysiloxane composition comprises at least the following components: an organopolysiloxane (A) represented by the following general formula: R13SiO(R12SiO)mSiR13 (where R1 is a monovalent hydrocarbon group, and “m” is an integer from 0 to 100); an organopolysiloxane (B) represented by the following average unit formula: (R2SiO3/2)a(R22SiO2/2)b(R23SiO1/2)c (where R2 is a monovalent hydrocarbon group, and “a”, “b”, and “c” are specific numbers); an organopolysiloxane (C) having in one molecule on average at least two silicon-bonded aryl groups and on average at least two silicon-bonded hydrogen atoms; and a hydrosilylation-reaction catalyst (D); is characterized by good fillability and curability and that, when cured, forms a cured body that possesses a high refractive index, high light transmissivity, and strong adhesion to various substrates.