Disclosed is a serial data conversion apparatus comprising: a video signal packet conversion unit for converting a characteristic signal of a video signal into a video signal characteristic packet and simultaneously converting a video signal into a video signal packet by the characteristic signal of a video signal, horizontal/vertical synchronization signals, and a video clock signal; an audio signal packet conversion unit for converting a characteristic signal of an audio signal into an audio signal characteristic packet and simultaneously converting an audio signal into an audio signal packet by the characteristic signal of an audio signal, left/right control signals, and an audio clock signal; a control signal packet conversion unit for converting a control signal into a control signal packet by an informing signal which informs a generation of a control signal; and a multiplexer for switching and selecting the video signal characteristic packet, the video signal packet, the audio signal characteristic packet, the audio signal packet, and the control signal packet by a certain format structure.