PURPOSE: To eliminate that a deemphasis circuit is not adversely affected by a switch circuit and to reduce influence of noise of a D/A converter by connecting the switch circuit not directly to the analog deemphasms circuit.

CONSTITUTION: A waveform data 'a1' is a digital signal indicating a recorded waveform signal itself, a selecting signal 'b1' selects a connection state of a switch circuit 13 based' on whether the waveform data 'a1' is processed with emphasis or not. Then, when data 'a1' is not processed with emphasis, it is processed with digital pre-emphasis by a digital pre-emphasis circuit 12. Emphasis quantity of digital pre-emphasis processing performed in the digital pre-emphasis circuit 12 is equal to emphasis quantity of the waveform data 'a1' in which emphasis processing is previously performed. Therefore, in an analog deemphasis circuit 15, even when the waveform data 'a1' is not processed with emphasis, it is processed in the same way as data processed with emphasis.