A filter device includes a filter that separates a steady component and a non-steady component included in an input signal, a synthesis unit that synthesizes the separated steady component and the separated non-steady component according to a given ratio, and an evaluation unit that evaluates the magnitude of the amount of the non-steady component in the input signal, wherein the synthesis unit sets the given ratio to a first ratio in an instance in which the evaluation unit determines the amount of the non-steady component to be equal to or less than a predetermined reference, and sets the given ratio to a second ratio, in which the proportion of the non-steady component is less than that of the first ratio, in an instance in which the evaluation unit determines the amount of the non-steady component to be greater than the predetermined reference.