PURPOSE: To clearly recognize visually a fault status and a state of guard/ release.

CONSTITUTION: Upon the receipt of a notice of fault occurrence from an LCU 5 in the guard state, a control means 1 allows a display pattern to be transited to a floor pattern of a floor having a fault, in which a symbol mark of a sensor sensing the fault is blinked in red. Thus, a person in charge of guard easily and visually and immediately recognize at which floor and at which location of the floor the fault occurs. Furthermore, when the floor pattern is displayed in the guard release state and a floor sensor senses a fault, the control means 1 changes a display color of a channel number of the sensor. Thus, the person in charge of guard easily confirms whether or not a person is resident on a floor or a door is open.