An ultrasound observation apparatus according to the present invention includes a frequency analysis unit for analyzing a frequency of an ultrasound signal thereby to calculate a plurality of frequency spectra depending on a reception depth and a reception direction of the ultrasound signal, a frequency band setting unit for setting a frequency band used for calculating a feature of each frequency spectrum calculated by the frequency analysis unit by use of parameters associated with a frequency spectrum in each of a plurality of candidate bands with mutually different bandwidths, a feature calculation unit for calculating a feature of each frequency spectrum based on the frequency band set by the frequency band setting unit, and a feature image data generation unit for generating feature image data displaying the information on the feature calculated by the feature calculation unit.
