A hardenable composition from which a hardening product of high adherence and high transparency or a hardening product of high toughness and high transparency can be produced. In particular, a hardenable composition comprising an organic compound having, per molecule, at least two reactive carbon to carbon double bonds and SiH groups (A), a silicon compound having, per molecule, at least two SiH groups (B), a hydrosilylating catalyst (C), a silane coupling agent and/or an epoxidized compound (D) and a silanol condensation catalyst (E). There is further provided a light emitting diode sealed with the hardening product obtained by hardening the hardenable composition.