According to one embodiment, a rotating blade noise reduction device for reducing noise from a flight vehicle including rotating blades, the device includes loudspeakers, one or more reference microphones, an estimator, and a processor. The loudspeakers are arranged coaxially in a circumferential form for each of the rotating blades. The reference microphones acquire noise generated from the rotating blades and control sounds generated from the loudspeakers. The estimator estimates angular frequencies of the rotating blades. The processor generates control signals so as to reduce sound pressures at the reference microphones, delays the control signals by time delays corresponding to the loudspeakers dependent on installation angles between the loudspeakers arranged coaxially in a circumferential form from a circle center, the angular frequencies estimated, and a number of the loudspeakers, and inputs the control signals to the loudspeakers.