PURPOSE: To provide a noise reduction device in which a noise reduction effect is not reduced even if a state in a vehicle is varied.

CONSTITUTION: In a noise reduction device which reduces a noise signal from a microphone 15 by controlling adaptively a tap value of an adaptive filter 7 generating a signal which reduces a noise inputted to the microphone 15 by an output from the microphone 15 and a signal from a transmission characteristic correcting section 8 which corrects a transmission characteristic until a signal generated in an adaptive filter 7 reaches the microphone 15, a transmission characteristic storage section 1 which stores a plural corrected transmission characteristics, an error detecting section 2 which detects an error signal from the microphone 15, and an optimum characteristic selecting section 3 which selects a transmission characteristic in which an error detected in the error detecting section 2 is made the minimum out of plural transmission characteristics stored in the transmission characteristic storage section 1 and sets it in the transmission characteristic correcting section 8 are provided.