To obtain a system, by which sure machine guard is conducted and the effect of energy conservation and secutity are improved when machinery are guarded while being interlocked with key control.

This system has a key box 2, in which the keys of doors (b), (c) for living rooms having entrances on the indoors are housed, and key housing and key extraction to and from a key housing section of each tenant are conducted on the basis of ID identification and the doors in each tenant are locked and released. A tenant (a) having an entrance only on the outdoors has a card reader 20 as an exclusive ID discrimination means separated from the ID discrimination means of the key box 2, and door control being different from the tenants (b), (c) having the entrances on the indoors and using no locking-release type key is performed on the basis of the result of the discrimination. The light putting-out control or invasion monitor of sharing sections on the indoors is carried out when there is no person in the tenants having the entrances on the indoors, and the light putting-out control of sharing sections on the outdoors is conducted when there is no person in all tenants including the tenant having the entrance only on the outdoors.