A dereverberation device includes an input instantaneous value calculation unit configured to calculate an input instantaneous value based on an input signal; a reverberation estimation unit configured to calculate a moving average of the input instantaneous value as a reverberation component; a gain calculation unit configured to calculate, with the input instantaneous value and the reverberation component, a first gain as a basic gain for the input signal; a gain suppression control unit configured to calculate, according to a ratio between the input instantaneous value and the reverberation component, a second gain changing within a range between a predetermined lower limit and a predetermined upper limit, thereby outputting a larger one of the first gain or the second gain as a third gain; and a gain processing unit configured to multiply the input signal by the third gain.