The present invention relates to a contactless torque sensor for steering system which is installed between an input shaft connected to a steering wheel and an output shaft connected to vehicle wheels and detects torsion generated by rotational manipulation of the steering wheel. The torque sensor comprises a magnetism generation unit coupled with the input shaft wherein north and south pole magnets are arranged along an outer circumference, a cylindrical magnetic shielding unit connected to the output shaft and comprising holes placed near the magnets, a magnetic detection unit distanced from the outer circumference of the magnetic shielding unit and detecting magnetism passing through the holes, and a magnetic detection sensor placed on an outer circumference of the magnetic detection unit and detecting torsion of the magnetism generation unit and magnetic shielding unit. The present invention allows detecting torque of the output shaft with magnetism induced only once.