PURPOSE: To suppress the current consumption of a battery, when a user forgets to switch off the power supply of an earpiece by cutting off the power supply when the reception level is lower than the prescribed value for the radio wave received by an earpiece.

CONSTITUTION: A no-signal detecting circuit 26 compares the output level of a high frequency amplifier 22 with the reference voltage and outputs a high-level signal while said outut level is higher than the reference voltage. A power supply cut-off circuit 27 turns on a switching element only when the high-level signal is produced from the circuit 26 and supplies the power of a battery 28 to the electric circuit of an earpiece 2. Then a switch of the main body of the hearing aid is operated to cut off the transmission output fed from a transmitter. Then the output signal of the circuit 26 is set at a low level, and the circuit 27 turns off the switching element to cut off the electric power so far supplied to a demodulator 23 and a sound amplifier 24 from the battery 28.