The present invention relates to a motor assembly comprising a core with an improved structure. An embodiment of the present invention provides a motor assembly comprising: a shaft configured to form a rotational axis of a motor; a rotor coupled to the shaft; and a plurality of cores provided along the circumference of the rotor and configured to form a magnetic path. The cores are spaced apart from the outer circumferential surface of the rotor by a predetermined distance and configured to surround at least a portion of the outer circumferential surface of the rotor, and each comprise: a pole shoe having a first surface parallel to the radial direction of the rotor; and a pole arm extending from the pole shoe toward the radially outer side of the rotor. Among the plurality of cores, the first surfaces formed on the pole shoes of adjacent cores are symmetrical with respect to the radial direction of the rotor.