With the noise reduction device (300), in identifying an acoustic transfer function that includes a path from the control speaker (340) to the error microphone (350) or the noise microphone (320) by outputting an identification sound from the control speaker (340) and detecting the identification sound with the error microphone (350) or the noise microphone (320), the identification controller (338) is configured to identify the acoustic transfer function by generating the identification sound from the white noise generator (337) when the seat detector (582) has detected that the seat is in the actual usage state for noise reduction.