To provide a curable composition useful for a coating agent for various optical materials, an encapsulant of LED, and a die bonding agent, which is excellent in heat resistance and light resistance and has solved problems such as a crack resulting from the internal stress of a cured product, occurrence of peeling, and warpage of a substrate, and to provide a cured product.

The curable composition includes, as essential ingredients, (A) a compound containing at least two carbon-carbon double bonds per molecule which are reactive with a SiH group, (B) a silicon compound containing at least two SiH groups per molecule, (C) a silane coupling agent, and (D) a hydrosilylation catalyst, wherein the composition includes 10-100 pts.wt. of the component (C) based on the sum of the components (A) and (B).