An audio device which is connectable to a portable player, the portable player being controllable by voice control, the audio device comprising: a sound output unit adapted to output sound, a sound source of which is a currently used audio source; a source selection unit configured to selectively set one of a plurality of audio source devices as the currently used audio source; a microphone; and a control voice processing unit, wherein, if the portable player is connected to the audio device, the source selection unit is configured to include the portable player in the plurality of audio source devices as one of the audio source devices, wherein, if the portable player is set as the currently used audio source, the sound output unit is configured to output sound transferred to the audio device from the portable player, wherein the control voice processing unit is configured to, if the portable player is connected to the audio device, transfer voice data of generated voice input from the microphone to the portable player, and to cause the portable player to perform voice control based on the voice data transferred to the portable player, characterized in that the control voice processing unit is further configured to: acquire a state of the portable player after the voice control is performed by the portable player, determine based on the acquired state whether or not a playback operation of the portable player is started by the voice control, check if the currently used audio source is the portable player, and if the playback operation of the portable player is started by the voice control and if the currently used audio source is not the portable player, cause the source selection unit to set the portable player as the currently used audio source. a sound output unit adapted to output sound, a sound source of which is a currently used audio source; a source selection unit configured to selectively set one of a plurality of audio source devices as the currently used audio source; a microphone; and a control voice processing unit, wherein, if the portable player is connected to the audio device, the source selection unit is configured to include the portable player in the plurality of audio source devices as one of the audio source devices, wherein, if the portable player is set as the currently used audio source, the sound output unit is configured to output sound transferred to the audio device from the portable player, wherein the control voice processing unit is configured to, if the portable player is connected to the audio device, transfer voice data of generated voice input from the microphone to the portable player, and to cause the portable player to perform voice control based on the voice data transferred to the portable player, characterized in that the control voice processing unit is further configured to: acquire a state of the portable player after the voice control is performed by the portable player, determine based on the acquired state whether or not a playback operation of the portable player is started by the voice control, check if the currently used audio source is the portable player, and if the playback operation of the portable player is started by the voice control and if the currently used audio source is not the portable player, cause the source selection unit to set the portable player as the currently used audio source. acquire a state of the portable player after the voice control is performed by the portable player, determine based on the acquired state whether or not a playback operation of the portable player is started by the voice control, check if the currently used audio source is the portable player, and if the playback operation of the portable player is started by the voice control and if the currently used audio source is not the portable player, cause the source selection unit to set the portable player as the currently used audio source.