An apparatus for guarding a pressure sensor for a washing machine is provided, which adjusts the water level required to wash laundries. The apparatus for guarding a pressure sensor includes a diaphragm built in a space part of a housing to operate in accordance with the water pressure of washing water being supplied through an inlet, a metal core mounted on an upper surface of the diaphragm through a coil spring, a first sensing part installed in a moving path of the metal core to output a signal required for adjustment of a water level of the washing water, a measurement part mounted on an upper surface of the metal core to ascend/descend along an operation path of the coil spring, a second sensing part mounted on an upper side of the space part to sense maximum and minimum positions of the measurement part, and a controller outputting a blocking signal to an inlet path of the inlet. According to the apparatus for guarding a pressure sensor, washing water more than or less than a prescribed amount is prevented from being supplied to the washing machine, and thus a uniform washing process is performed to improve the reliability of the washing machine. Also, the damage or corrosion of electric/electronic sub assembly of the washing machine due to the overflow of the washing water is prevented to prolong the lifespan of the washing machine.