A silicone resin composition for sealing an optical semiconductor element includes (A) (A-1) an organopolysiloxane having a resin structure which contains at least two alkenyl groups in one molecule, the alkenyl groups being present at 10 to 70 mol % of the total substituent groups bonded to silicon atoms, (B) an organopolysiloxane oligomer having at least two alkenyl groups in one molecule and 2 to 5 silicon atoms, (C) an organohydrogenpolysiloxane which contains at least one hydrosilyl group and may have an alkoxy group or hydroxyl group in one molecule, and (D) an addition reaction catalyst, and is capable of providing a transparent cured product.