Embodiments relate to a polythiourethane-based plastic lens. When a polythiourethane-based plastic lens is polymerized according to the embodiment, the types, contents, and the like of the polythiol compounds and the isocyanate compounds are adjusted to control the storage moduli at room temperature and high temperatures, their variations, the energy attenuation (KEL) obtained therefrom, and the glass transition temperature, whereby the polythiourethane-based plastic lens thus obtained is enhanced in impact resistance and thermal resistance.