An audio signal processing device includes a first microphone configured to pick up audio and output a first audio signal; a second microphone configured to pick up the audio and output a second audio signal; a first frequency converter configured to convert the first audio signal to a first audio spectrum signal; a second frequency converter configured to convert the second audio signal to a second audio spectrum signal; an operating sound estimating unit configured to estimate, based on the correlation between a sound emitting member that emits an operating sound and the first and second microphones, an operating sound spectrum signal indicating the operating sound, by calculating the first and second audio spectrum signals; and an operating sound reducing unit configured to reduce the estimated operating sound spectrum signal from the first and second audio spectrum signals.