1. In a rear monitoring camera of automobile including a controller for controlling the overall operation of a system, a body for protecting various components inside the camera, a photographing section installed at the front of the body and adapted to photograph surrounding objects or background, a printed circuit board mounted inside the body and adapted to electrically connect the various components to each other, and a switching device for left/right image reversion electrically connected to the printed circuit board and adapted to select either a normal image or a mirror image displayed on a monitor, the switching device for left/right image reversion comprising: a magnet for generating a magnetic force; a pair of magnet insertion holes formed at a rear side of a casing connected to the printed circuit board mounted inside the body of the camera in such a manner as to be spaced apart from each other by a predetermined distance such that the magnet is inserted thereinto, and adapted to form a normal image and a mirror image, respectively; a magnet sensor for turning on a switch embedded therein by means of a magnetic field generated in the magnet when the magnet is inserted into the magnet insertion hole for normal image; a power supplying section for supplying an electric power to the magnet sensor; a signal stabilizing circuit for stabilizing the electric power applied from the power supplying section when the switch embedded inside the magnet sensor is turned on so as to generate a normal image control signal(High); and a timing section for providing the normal image control signal(High) generated from the signal stabilizing circuit to the controller to display a normal image on the monitor.