An earphone device of an ear-hole insertion type having a noise cancelling function, the earphone device comprising: a left channel output unit comprising a left channel housing unit and a left earpiece detachably mounted onto the left channel housing unit, wherein the left earpiece in use is inserted into the left ear-hole of a user, and wherein the left channel housing unit accommodates a left channel driver unit for outputting a left channel sound; and a right channel output unit comprising a right channel housing unit and a right earpiece detachably mounted onto the right channel housing unit, wherein the right earpiece in use is inserted into the right ear-hole of a user, and wherein the right channel housing unit accommodates a right channel driver unit for outputting a right channel sound, wherein a microphone to record external sound for noise cancelling and a battery for supplying power for noise cancelling are accommodated in each of the left and right channel housing units, and wherein the microphone in the left channel housing unit is looking in an opposite direction to the output direction of the left channel driver unit and the microphone in the right channel housing unit is looking in an opposite direction to the output direction of the right channel driver unit; wherein: the left channel output unit comprises circuitry configured to detect a remaining battery level of the battery accommodated in the left channel housing unit; the right channel output unit comprises circuitry configured to detect a remaining battery level of the battery accommodated in the right channel housing unit, the circuitry of the right channel output unit being configured to communicate data with the circuitry of the left channel output unit; characterised in that the circuitry of one of the left and right channel output units is configured to simultaneously turn off both the left and right channel output units when a remaining battery level of any one of the left and right channel output units is less than a predetermined level. a left channel output unit comprising a left channel housing unit and a left earpiece detachably mounted onto the left channel housing unit, wherein the left earpiece in use is inserted into the left ear-hole of a user, and wherein the left channel housing unit accommodates a left channel driver unit for outputting a left channel sound; and a right channel output unit comprising a right channel housing unit and a right earpiece detachably mounted onto the right channel housing unit, wherein the right earpiece in use is inserted into the right ear-hole of a user, and wherein the right channel housing unit accommodates a right channel driver unit for outputting a right channel sound, wherein a microphone to record external sound for noise cancelling and a battery for supplying power for noise cancelling are accommodated in each of the left and right channel housing units, and wherein the microphone in the left channel housing unit is looking in an opposite direction to the output direction of the left channel driver unit and the microphone in the right channel housing unit is looking in an opposite direction to the output direction of the right channel driver unit; wherein: the left channel output unit comprises circuitry configured to detect a remaining battery level of the battery accommodated in the left channel housing unit; the right channel output unit comprises circuitry configured to detect a remaining battery level of the battery accommodated in the right channel housing unit, the circuitry of the right channel output unit being configured to communicate data with the circuitry of the left channel output unit; characterised in that the circuitry of one of the left and right channel output units is configured to simultaneously turn off both the left and right channel output units when a remaining battery level of any one of the left and right channel output units is less than a predetermined level. the left channel output unit comprises circuitry configured to detect a remaining battery level of the battery accommodated in the left channel housing unit; the right channel output unit comprises circuitry configured to detect a remaining battery level of the battery accommodated in the right channel housing unit, the circuitry of the right channel output unit being configured to communicate data with the circuitry of the left channel output unit; characterised in that the circuitry of one of the left and right channel output units is configured to simultaneously turn off both the left and right channel output units when a remaining battery level of any one of the left and right channel output units is less than a predetermined level.