An ultrasound observation apparatus includes: a transmitting-and-receiving unit that: generates an electrical transmission drive wave for generating an ultrasound pulse to be transmitted by an ultrasound probe； outputs the transmission drive wave to the ultrasound probe； and receives an electrical echo signal from the ultrasound probe； an analysis unit that analyzes a frequency of the echo signal to calculate a frequency spectrum of the echo signal； a setting unit that sets, in accordance with the transmission drive wave, a frequency band used in calculating a feature of the frequency spectrum； a correction unit that corrects intensity of the frequency spectrum in the frequency band, using a correction amount defined according to the transmission drive wave, to calculate a corrected frequency spectrum； and an approximation unit that approximates the corrected frequency spectrum calculated by the intensity correction unit, in the frequency band, to extract a feature of the corrected frequency spectrum.
