A pleasant sound making device processes temporal variation characteristics in nature such that a frequency component and a peak frequency component in a frequency band which coincide with or are approximate to a housing of an indoor unit provided with a driving part (a fan, a motor, etc.) do not coincide with or are not approximate to the housing, on the basis of subjective view and physiological response evaluations of humans, and operates the driving part with a signal based on the processed waveform.
