PURPOSE: To improve control to prevent disasters by setting a sensor for detecting the locking of a dead bolt directly at the innermost section of a dead bolt locking hole, and by receiving its signal to start the precaution state of concentrated monitoring.

CONSTITUTION: At the innermost section of a grout avoiding case 10 confronted with a dead bolt lock hole 7 at an interval between them, the sensor of a micro-switch 9 or the like is set. After that, a door is locked, and a dead bolt 5 is projected to the hole 7 to be locked together, and the switch 9 is pressed with the tip of the bolt 5, and locking signal S1 is generated. After that, the signal S1 is received by an individual control board 13 set on each floor and in each room or the like. After the group of the locking signals S1 of all of the doors is received, the precaution state starting signals S2 of a window sensor 14, a fire sensor 15, and an infrared sensor 16 are generated to a concentration control room 17 from the control board 13, and after that, in the room 17, the action of the group of the control boards 13 is monitored. As a result, locking can be prevented from being detected in error and security and a state to prevent disasters can be speedily established.