Patent ID: 8037639

Claim:
A door opening and closing device for moving a door through rotation of a rotation shaft obtained by transmitting a drive force of a motor to the rotation shaft through an electromagnetic clutch arranged around the rotation shaft, the door opening and closing device comprising: a rotation sensor including: a magnetic member provided adjacent an end of the rotation shaft and rotationally moved according to the rotation of the rotation shaft, and a detecting element fixed a predetermined distance from the magnetic member and configured to detect a magnetic flux that is generated by the magnetic member, said magnetic flux crossing a direction of a magnetic flux that is generated by the electromagnetic clutch such that the detecting element is not influenced by the magnetic flux from the electromagnetic clutch; a motor base configured to fix the motor to a device base; and a sensor case configured to house the rotation sensor therein, wherein the motor base is attached to the sensor case such that the end of the rotation shaft extends outside of the motor base and the magnetic member is rotatably arranged on a longitudinal axis which is offset relative to a longitudinal axis of the rotation shaft.