An audio information detector extracts frequency information on audio data from a packet called an ASP in the HDMI standard and outputs the extracted frequency information to a frequency divider as audio information. The frequency divider determines a frequency division ratio based on the audio information, divides the frequency of a PLL clock signal output from an analog PLL circuit by the frequency division ratio and outputs the resultant signal as a comparison clock signal. The analog PLL circuit performs feedback control such that the comparison clock signal and a reference clock signal are synchronized with each other, and generates an audio clock signal obtained by performing frequency multiplication or division on the reference clock signal.