A signal processing device for detecting, from an input signal expressing data series, the data, including: a sampling clock generating unit for generating, from a driving clock with a predetermined cycle, multiple sampling clocks with mutually different phases and the same cycle as the cycle; a sampling data generating unit for sampling the input signal using the multiple sampling clocks, and generating a plurality of sampling data; a phase comparison data generating unit for generating phase comparison data indicating phase shifting as to the input signal of the sampling clock using the sampling data for each sampling clock; and a data generating unit for generating the data for each sampling clock using the sampling data, and selecting the data of the sampling clock having the phase closest to the phase of the input signal as the original data expressed with the input signal, based on the phase comparison data.