SIGNAL PROCESSING DEVICE, SENSOR DEVICE, AND SIGNAL PROCESSING METHOD

A signal processing device for performing processing for reducing noise in a displacement amount measured on a basis of light reflected from a detection object includes a moving-average calculating unit that performs moving average calculation for an input signal to reduce a noise component included in the input signal and an infinite impulse response filter that reduces a noise component included in an input signal by digital signal processing. A filter coefficient of the infinite impulse response filter is determined on a basis of a difference between a first calculation result output by the moving-average calculating unit and a second calculation result output by the infinite impulse response filter when a same signal is input to the moving-average calculating unit and the infinite impulse response filter.