To make the carrier of a key clear, and to prevent taking-out by anyone while obviating a mistake at the time of a return.

This safekeeping box 1 has hooks 3 for keeping keys 2 in custody, hook switches detecting the presence of the keys 2 and locking devices locking covers. Key numbers input by ten keys 5 release the locking devices when the keys are brought to the safekeeping state or the state of taking-out on the basis of outputs from the hook switches, and a control section 4 ringing an alarm buzzer 9 is mounted when the keys are not brought to the above- mentioned state.