A linear motor includes a stator having field poles arranged linearly with opposing polarities arranged in an alternating manner; and a rotor having an armature core with teeth that faces a pole face of the field poles with a gap, and coils wound around the teeth. The stator and the rotor are supported in a slidable manner, a direction perpendicular to a sliding direction of the rotor and in parallel with the pole face is defined as a stacking direction. A head of each of the teeth has an extended portion extended in the sliding direction. At least heads of the teeth arranged at both ends of the armature core along the sliding direction is divided into a plurality of areas along the stacking direction. At least one of extended portions arranged on adjacent areas is extended by a different length along the sliding direction.