A data processing device operable to connect a display device, and operable in at least one of a power-off state, a recording standby state, and a power-on state, comprising: a receiving unit operable to receive a control signal from the display device connected to the data processing device; a transmitting unit operable to transmit a control signal to the display device externally connected, a signal processing unit operable to generate video data and/or audio data, a drive unit operable to store data including the video data and/or the audio data to a recording medium; a power control unit operable to control electric power supplied to the signal processing unit and the drive unit, a front panel unit operable to display the operation state of the data processing device, wherein the power control unit supplies the electric power to at least the drive unit in the power-on state and the recording standby state, and stops the supplying of the electric power to at least the drive unit in the power-off state, wherein the front panel unit indicates that power is on in the power-on state, and indicates that power is off in the recording standby state and the power-off state, and wherein the power control unit switches the power state from the recording standby state to the power-on state when the receiving unit receives at least a signal instructing start of a recording operation from the display device, in the recording standby state, wherein the transmitting unit periodically transmits, in the recording standby state, to the display device a power state confirmation signal inquiring a power state of the display device, wherein the power control unit changes the power state from the recording standby state to the power-off state, when the receiving unit does not receive a reply signal from the display device within a predetermined time since the power state confirmation signal is transmitted, or when transmission of the power state confirmation signal fails. a receiving unit operable to receive a control signal from the display device connected to the data processing device; a transmitting unit operable to transmit a control signal to the display device externally connected, a signal processing unit operable to generate video data and/or audio data, a drive unit operable to store data including the video data and/or the audio data to a recording medium; a power control unit operable to control electric power supplied to the signal processing unit and the drive unit, a front panel unit operable to display the operation state of the data processing device, wherein the power control unit supplies the electric power to at least the drive unit in the power-on state and the recording standby state, and stops the supplying of the electric power to at least the drive unit in the power-off state, wherein the front panel unit indicates that power is on in the power-on state, and indicates that power is off in the recording standby state and the power-off state, and wherein the power control unit switches the power state from the recording standby state to the power-on state when the receiving unit receives at least a signal instructing start of a recording operation from the display device, in the recording standby state, wherein the transmitting unit periodically transmits, in the recording standby state, to the display device a power state confirmation signal inquiring a power state of the display device, wherein the power control unit changes the power state from the recording standby state to the power-off state, when the receiving unit does not receive a reply signal from the display device within a predetermined time since the power state confirmation signal is transmitted, or when transmission of the power state confirmation signal fails.