PURPOSE: To allow all the operators to be informed of the happening of anomality even if the equipment which produces noise when an anomal state is happened.

CONSTITUTION: At a working site in a tunnel pit 3 where the equipment such as an excavating machine 2 which produces noise in operation, an emergency alarm device 1 is installed. An emergency switch 5, alarm device 5 which is connected with the emergency switch 4 and dispatches alarm when the switch 4 is turned ON, and an alarm lamp 6 which is connected with the emergency switch 4 and emits light when the switch is turned ON are provided. The equipment such as the excavating machine 2 is connected with the emergency alarm device 1, so that the operation is suspended when the emergency switch 4 is turned ON.