Linear motor and stage device

To reduce the overall size and weight of a linear motor. A linear motor (1) is provided with a field system (10) and an armature (20). The field system (10) includes two yoke plates (11a, 11b) respectively having mutually opposing surfaces; and a first magnet array (64) wherein multiple magnets (14) for X-direction movement are disposed in the X-direction along the respective opposing surfaces of the two yoke plates (11a, 11b). The armature (20) has a first armature coil array (73) wherein multiple single-phase coils (23) for X-direction movement are disposed in the X-direction, said first armature coil array (73) facing the first magnet array (64) via a magnetic gap. In the first armature coil array (73) and the first magnet array (64), the single-phase coils (23) for X-direction movement are wound with the X-direction as an axial center, and the magnets (14) for X-direction movement are disposed such that the respective polarities alternate along the X-direction and such that the magnets (14) in each pair of two mutually opposing magnets (14) for X-direction movement have the same polarity.