To enhance safety by providing a first detecting device for detecting an obstruction within a monitoring area distant from a construction equipment, and a second detecting device for detecting the contact of the obstruction with the construction equipment.

When a person gets into a monitoring area E2, the ultrasonic sensor of a first detecting device 3 detects it and outputs a signal to a controller 21. An external alarm 18 is driven by the controller 21 to alarm the person by an alarm light, and an internal alarm 19 is also driven to inform an operator of the presence of the person by an alarm light. When the ultrasonic sensor detects that the person intrudes to a monitoring area E1, the alarms 18, 19 generate a voice and a buzzer sound together with the alarming by the alarm lights, respectively. When the person contacts a bumper 5, further, the contact type sensor of a second detecting device 6 detects it, and outputs a stop command signal to an engine together with the alarm light, voice and buzzer sound by the alarms 18, 19.