Abstract: A door locking device wherein first and second field magnets are disposed at respective stationary positions opposite to each other through an axial air gap; the first field magnet has 2P (P: an integer of at least 2) contiguous poles of alternating N and S polarity and is formed in a torus shape; the second field magnet has n pole(s) (n: an integer of at least 1) of alternating N and S poles and is formed so as to define a space capable of receiving a swingable driven gear in the plane opposite to a rotatable coreless armature and hence not to become a complete torus form; a rotatable coreless armature is rotatably provided between the first and second field magnets; a commutator is provided on the rotatable coreless armature so as to rotate integrally therewith; brushes coming into movable contact with the commutator are provided on its corresponding stationary side; a driving gear rotating integrally with the rotatable coreless armature is disposed concentrically with the armature; a back yoke for the seco