An electronic fence transmitter for self-adjusting the receiving distance is comprised of a fence wire buried in a yard, a voltage detector that is connected in series to the fence wire and a comparator for comparing the detected voltage of the voltage detector with a reference voltage. A voltage applied to the fence wire is automatically adjusted according to a signal inputted from the comparator and increasing gradually until a value of the detected voltage is larger than the value of the reference voltage. Accordingly, a distance for receiving the signal from the fence wire is set as constant without regard to an installation length or area of fence wire.