An audio processing device includes a feature extraction unit and signal generating unit. The feature extraction unit is configured to extract a feature quantity of a first audio signal for each of a plurality of periods. The signal generating unit is configured to for generate a second audio signal by time axis expanding/compressing either a section of the first audio signal in which the feature quantity is steadily maintained for a period time, or a section of the first audio signal in which a fluctuation of the feature quantity is repeated and excluding from the time axis expanding/compressing a section of the first audio signal in which a fluctuation of the feature quantity is not similar to that of other sections of the first audio signal.