Abstract: A device is mounted inside the interior space defined by a cabinet to alert a supervising adult that a child has opened the cabinet door. The device is mounted so that an outer face of its housing is directed outwardly adjacent to the opening closed by the door. A perpendicular mounting end is attached to an inner sidewall surface of the cabinet. An activator switch has a lever or button biased to project outwardly from the outer face of the housing. The closing of the cabinet door moves the projecting lever into a depressed position. When the cabinet door is opened, movement of the lever into a projecting position activates an audible alarm. In alternate embodiments, one or more of the components of the device may be provided in a separate housing part mounted outside the cabinet.