PURPOSE: To enable the return of a key to be detected by arranging a key holding box formed with a door to be opened when intrinsic identification signal coincides with identification signal entered previously into a directory, and a photoelectric switch for detecting whether the key is held in the key holding box or not.

CONSTITUTION: When a key 16 is held in a key holding box 15, then the key 16 is detected by a photoelectric switch 17, and the output of contact signal 18 is directed to an air conditioner 8, a lighting equipment 9, an elevator 10, and a crime-preventing shutter 11. After that, by a resident, the input of a card to a magnetic card reader 6A is provided, and when the card is identically checked, then by command from a controller 1, the shutter 11 of a passage port and the lock of a passage port door 13 are released. After that, the input of a card to the magnetic card reader 6 of a key box 7 is provided, and when the card is identically checked, then the input of 'opening' command to the box 7 from the controller 1 is provided. Besides, when the box 7 is opened, then a key switch 7b works, and by the controller 1, the air conditioner 8 and the elevator 10 are started and the lighting equipment 9 is lit.