Resin composition for optical lens having light weight and high refractive index, and the optical lens using it

A resin composition for optical lens having light weight and high refractive index is provided to realize high refractive property while holding the advantages of plastic lens with impact resistance, and to ensure excellent optical property including solvent resistance, dyeability, heat resistance and high Abbe number. A resin composition for optical lens having light weight and high refractive index is obtained by reacting a polythiol compound 30~70 weight% having an ether group indicated as the chemical formula 1 and polydi isocyanate 30~70 weight%. In the chemical formula 1, X is alkylene of which the carbon number is 10 or less; Y is a polyhydric alcohol more than a secondary alcohol; L is 1~3, m is 0~10, and n is 0~10, wherein m and n does not be 0 at the same time.