To improve the reproduction quality of audio or music included in digital audio data by eliminating data oversupply or data undersupply at a data reception circuit when the data reception circuit is not synchronized with a data transmission circuit.

A period measurement section 1 measures a period of a transmission LR clock LRs via a fast sampling clock fsr synchronized with a reception LR clock LRr and having a predetermined frequency higher than the frequency of the reception LR clock LRr. A data interpolation section 2 calculates a period difference between the measured period of the transmission LR clock LRs and the period of the reception LR clock LRr, and at each output timing of the reception LR clock LRr, calculates a phase of the transmission LR clock LRs at the output timing according to the calculated period difference and linearly interpolates audio data Da before and after the output timing according to the calculated phase to generate interpolated audio data Dinsr.