An audio device connected to an electronic device is provided. The audio device connected to an electronic device includes an audio side connector comprising a microphone terminal that outputs a microphone signal to the electronic device, at least one audio terminal that receives an audio signal from the electronic device, an active noise cancelling (ANC) terminal, and a ground terminal, an ANC block that is driven by power input from the electronic device to remove noise around the audio device, an ANC power source unit that is provided in the electronic device and applies power input via the ANC terminal to the ANC block as drive power, and an on/off switch unit that controls the ANC power source unit, wherein the ANC terminal is included in any one of the areas of the microphone terminal, the audio terminal, and the ground terminal.