There is provided a signal processing device comprising a combination unit (3) configured to combine plural element signals based on plural physical quantity signals including signal components in accordance with desired physical quantities, respectively, by the number of times equal to or greater than a number of the plural physical quantity signals, and to output combined signals different from each other; a measuring unit (4) configured to sequentially receive the combined signals output from the combination unit (3); and a computing unit (5) configured to compute signal components based on the desired physical quantities from signals that are generated based on the combined signals sequentially output from the measuring unit.