A 4,9-bis(glycidyloxy)diamantane and a 4,9-bis[(3-ethyloxetane-3-yl)methyloxy]diamantane are novel curable diamantane compounds, and cured bodies thereof are useful as encapsulants exhibiting excellent light resistance and heat resistance, and can be favorably used, for example, as encapsulants for near ultraviolet LEDs and white LEDs.