Abstract: A signal detection device includes a measurer, an arithmetic operation unit, and signal period detector, and detects information such as a cardiac cycle with high accuracy by causing resonance of only a signal such as a heartbeat, the signal having strong pulse characteristics. The measurer measures a signal. The arithmetic operation unit performs nonlinear arithmetic operation processing for amplifying a pulse-like component of the signal measured by the measurer and suppressing a component other than the pulse-like component of the signal measured by the measurer. The signal period detector detects a periodic signal from an output of the arithmetic operation unit.