A sensing device comprising: a first cover made of a metal material; a second cover coupled to the first cover; a rotor disposed inside the second cover; a first magnet disposed between the second cover and the rotor, the first magnet being fixedly attached to an outer circumferential surface of the rotor; a stator disposed between the first magnet and the second cover; a seating part disposed between the first cover and the rotor; a second magnet disposed on the seating part; a circuit board disposed on a bottom surface of the second cover; and a first Hall sensor and a second Hall sensor disposed on the circuit board, the first Hall sensor being disposed to detect an amount of magnetization of the stator generated due to an electrical interaction between the first magnet of the rotor and the stator, wherein the first cover includes an upper plate having an opening and side plates (120, 150) extending axially from the upper plate, wherein the side plates include an outer side plate disposed outside the upper plate and an inner side plate disposed inside the upper plate; the outer side plate of the first cover includes a first groove formed at a position corresponding to the second Hall sensor and second grooves spaced apart from the first groove, and wherein the outer side plate blocks the second magnet from the second Hall sensor such that the second magnet is positioned to face the second Hall sensor at the position of the second Hall sensor through the first groove, wherein the stator includes a collector coupled to the second cover, and wherein the second grooves are disposed close to side surface ends of the collector. a first cover made of a metal material; a second cover coupled to the first cover; a rotor disposed inside the second cover; a first magnet disposed between the second cover and the rotor, the first magnet being fixedly attached to an outer circumferential surface of the rotor; a stator disposed between the first magnet and the second cover; a seating part disposed between the first cover and the rotor; a second magnet disposed on the seating part; a circuit board disposed on a bottom surface of the second cover; and a first Hall sensor and a second Hall sensor disposed on the circuit board, the first Hall sensor being disposed to detect an amount of magnetization of the stator generated due to an electrical interaction between the first magnet of the rotor and the stator, wherein the first cover includes an upper plate having an opening and side plates (120, 150) extending axially from the upper plate, wherein the side plates include an outer side plate disposed outside the upper plate and an inner side plate disposed inside the upper plate; the outer side plate of the first cover includes a first groove formed at a position corresponding to the second Hall sensor and second grooves spaced apart from the first groove, and wherein the outer side plate blocks the second magnet from the second Hall sensor such that the second magnet is positioned to face the second Hall sensor at the position of the second Hall sensor through the first groove, wherein the stator includes a collector coupled to the second cover, and wherein the second grooves are disposed close to side surface ends of the collector.