According to one embodiment, a noise reduction device includes speakers, microphones, and a processing circuit. The speakers are arranged around a rotor and emit control sound based on control signals. The microphones are arranged around the rotor and convert the control sound and noise emitted by the rotor into microphone signals. The processing circuit generates the control signals for reducing acoustic power in positions of the microphones, based on the microphone signals, rotation speed of the rotor, and a phase of noise that reaches the microphones from the rotor.