Abstract: An adapter junction box is provided that consists of an upper and a lower shell, a base strip held in a base holder of the lower shell, a spring placed in each bushing segment on the top side of the base strip. A guard plate is put on the other end of the spring by a sleeve formed on the bottom side of the guard plate, so that the V-shaped heads of the sleeve of the guard plate are opposite to V-shaped guide heads of the bushing segment on the base strip, wherein the guard plate blocks the sockets. When a plug is correctly plugged into the sockets of the adapter junction box, the guard plate is turned at an angle by sliding the V-shaped heads on the V-shaped guide head as the guard plate is moved down by the pins of the plug, so that the path of the pins is cleared and the pins of the plug can engage the conducting strips. When a foreign object is plugged into one socket, the guard plate is pressed unevenly so that the guard plate is blocked and unable to turn to expose the conducting strips.