A curable composition and use thereof are provided. The exemplary curable composition can show excellent processability and workability. Also, the curable composition can have a high refractive index before or after curing. The composition has low moisture permeability before or after curing and shows excellent crack resistance, thermal shock resistance, adhesive property and hardness. In addition, the composition does not cause color change such as whitening under a high-temperature or high-humidity condition, and does not exhibit stickiness on a surface thereof. The curable composition may be used as an adhesive material or as an encapsulation material for semiconductor devices such as an LED, a CCD, a photo coupler, or a photovoltaic cell.