Disclosed is a noise suppression device capable of better noise suppression by means of a simpler structure and with a lighter computational load. A noise suppression device (100) has a noise suppression processor (150) to estimate the required information only from the observed information, which is the required information corrupted by noise. A correlator (154) calculates the correlation of the estimation error when the state quantity, which contains the required information, of the system at time n+1 was estimated from the information until time n or time n+1 for the observed information at only time n. A weighting coefficient calculator (156) uses the correlation calculated by the correlator (154) for the observed information at only time n to calculate the weighting coefficients for specifying the relationships of the optimum estimate of the state quantity at that time based on the information until time n+1, the optimum estimate of the state quantity at time n+1 based on the information until time n, and the estimation error of the observed quantity including the observed information. An optimum estimate calculator (158) uses the weighting coefficients calculated by the weighting coefficient calculator (156) for the observed information only at time n to calculate the optimum estimate of the state quantity at that time based on the information until time n or time n+1.