An apparatus for preventing short circuit including an input/output terminal electrically connected, via a second external power line, to an external apparatus that is electrically connected to one of a driving voltage supply or a ground via a first external power line; an internal power line electrically connecting one of the driving voltage supply or the ground to the input/output terminal; a switch mounted on the internal power line to energize or block the internal power line; a variable resistor mounted on the internal power line; and a controller determining whether the input/output terminal is shorted based on a measurement current value of a current flowing through the internal power line and controlling a set resistance value of the variable resistor based on whether the input/output terminal is shorted.