PURPOSE: To reduce the hard scale, by dividing an alarm for every group, securing operation for any of the alarms among those groups to display the group-based alarm and then giving an indication for selection of an alarm among the groups.

CONSTITUTION: A multiplex signal (a) of an alarm produced from each of the devices which are decentralized is separated by a separating circuit 1. A flip-flop 4 is used for this separation. The separated signals are brought to continue for a certain period at a timer circuit 5 respectively to produce an alarm corresponding to the group. After this, when a group designation is given to the produced alarm by an operator, the desingated group pulse is produced. Furthermore a detailed alarm is selected through a selecting circuit 3 with use of a selection indicatibg signal to produce an alarm. In such way, a separation can be made for every group with installation of a timer even in case many alarms have to be separated.