There is provided an area monitoring sensor, an operating state of which a user can be checked without approaching a hazard source. An area monitoring sensor, which detects an intruding object in a monitoring area to generate a stop signal for stopping an operation of an external device, is configured of: a measurement unit; a display unit that includes a screen display part for displaying an operating state of the measurement unit on a screen; and a wiring cable for detachably connecting the measurement unit and the display unit, to supply electric power between the measurement unit and the display unit.