Abstract: An electrical nerve stimulator includes a main probe device receiving a current signal generated by a current generator. The main probe device includes a probe disposed in a housing and having a tip extending outwardly of a tubular end portion of the housing, and a cover mounted detachably on the end portion of the housing and having a flexible absorbent cap portion for covering the tip of the probe. The main probe device is operable so as to generate a stimulating signal based on the current signal from the current generator and to output the stimulating signal through the probe.