Open/close body drive device

An open/close body drive device, which is capable of motor-driving an open/close body attached to a motor vehicle so as to open and close said open/close body,

• comprising:
• a DC brushless motor acting as a drive source;
• a motor drive unit switching drive voltage applied to stator coils on the basis of a rotational position and rotation number of a rotor, which have been detected by a plurality of magnetic pole sensors for detecting positions of magnetic pole positions of a rotor magnet;
• and
• a control unit for controlling said motor drive unit so as to open and close said open/close body on the basis of detection signals of the magnetic pole sensors,
• wherein said control unit determines that the sensor has failed and temporarily stops drive of said DC brushless motor when said control unit detects an abnormal logic as a detection pattern of the magnetic pole sensors, and said motor drive unit generates a phase switching signal to prolong one of electric connection patterns for performing sensorless drive when restarting said DC brushless motor.