The curable resin composition according to the present invention includes a polyorganosiloxane (A), a silsesquioxane (B), an isocyanurate compound (C), and a silane coupling agent (D). The polyorganosiloxane (A) is a polyorganosiloxane approximately devoid of aryl groups. The silsesquioxane (B) includes a ladder-like silsesquioxane. The curable resin composition has excellent heat resistance, transparency and flexibility. It offers superior reflow resistance and barrier properties to a corrosive gas.