A washing machine having a dual-purpose sensor capable of detecting a degree of vibration generated during a dewatering step as well as measuring detergent levels present in the water. The washing machine having a sensor unit installed with respect to an outer tub for holding water. The washing machine includes a microcomputer having an input port receiving an applied voltage, the input port electrically connected to a supply voltage; first and second electrodes, installed so as to be submerged in the water of the outer tub, wherein the first electrode is electrically connected to the supply voltage and the second electrode is electrically connected to ground, to thereby generate the applied voltage for input to the input port of the microcomputer; a spherical conductor disposed adjacent to the electrodes; and a support for supporting the spherical conductor.