To provide a door device which has a crime-preventive function imparted thereto, without power supply to a door.

According to the door device, a cover 22 is detachably arranged on a mechanical lock outer portion 15c so as to cover an insertion port for a mechanical key for a mechanical lock. Therefore the door lock cannot be locked/unlocked by the mechanical key without removing the cover 22 from the mechanical lock outer portion 15c. Then a stile 13 of the door has a first switch 26 arranged therein at a location opposed to a permanent magnet 23, for detecting presence/absence of the cover 22 on a non-contact basis. The first switch 26 is formed of a reed switch which is turned on/off based on detection of a magnetic field generated by the permanent magnet 23 embedded in the cover 22. When the first switch 26 detects that the cover 22 is removed, the door device 11 activates a buzzer arranged in the stile 13. In this manner the door device 11 has the crime preventive function imparted thereto, without power supply to the door 12.