There is provided a signal processing apparatus includes a sampling clock generator for generating a sampling clock by delaying, a phase of a driving clock having the same frequency as a carrier-wave; a logic data generator for generating logic data in synchronization with the driving clock, that the logic data are generated by using the driving clock generated to sample a modulation signal obtained by shifting a phase of the carrier-wave; a sampling bit-string generator for generating a sampling bit-string by shifting the logic data; a phase-error data generator for using a bit-string corresponding to one cycle of the carrier-wave extracted from the sampling bit-string to generate phase-error data between a phase of the bit-string and the phase of the carrier-wave; and an extraction position determination unit for determining, based on the phase-error data, an extraction position of the bit-string having a phase similar that of the carrier-wave.