To dispersedly keep keys by making external dimensions of a key holder storage box the one surface of which is opened to be buried on a wall surface the same as a switch box of a JIS standard.

An outer case 3 is a box type body with one surface open and is furnished with at least more than one key holders 4 inside, and it is buried on a wall surface in the neighbourhood of an elevator hall and a staircase on a floor having a room corresponding to a key to be kept. Thereafter, as external dimensions of the case 3 are made the same as a switch box of a JIS standard, it becomes possible to bury the case 3 on the wall surface as easily as conventional burying work of the switch box. Thereafter, when a key 7 is pushed into an insertion hole in the same way as before, for example, a latching device to be controlled by an electromagnetic actuator, etc., works and the key 7 is engaged in the holder 4, and when an ID card is inserted into a magnetic card reader, the key is disengaged and can be taken out of the holder 4. Consequently, it is possible to easily install it and accordingly, it is possible to dispersedly arrange key holder devices at desired points.