An audio device includes a jack slot detachably connectable with an audio jack; a detection and monitor unit constantly supplying a first voltage and a second voltage to the jack slot and detecting whether a conductive material is attached to the jack slot depending on changes in the first and second voltages, in a first detection mode; and a determination unit determining whether the conductive material is the audio jack depending on a change in at least one of the first and second voltages in response to detecting attachment of the conductive material. In response to determination by the determination unit that the conductive material is not the audio jack, the detection and monitor unit in a second detection mode monitors a change in the at least one of the first and second voltages while periodically supplying the first and second voltages to the jack slot.