An ultrasound observation apparatus includes: an ultrasound image generator that generates data of an ultrasound image based on an ultrasound wave signal； a region of interest setting unit that sets a first region of interest set in advance within the ultrasound image and a plurality of second regions of interest including at least the first region of interest, when receiving an input of a freeze instruction signal that sets a display on a display device as a still image； a reference value calculating unit that calculates reference values according to ultrasound wave signals of the first region of interest and the plurality of second regions of interest, respectively； and an elastic image generator that sets a display region of interest in which the reference value of the first region of interest and the reference values of the second regions of interest have a predetermined correlation and the second regions of interest are maximized, and generates data of an elastic image having a display mode according to hardness of the display region of interest. As a result, in ultrasound elastography, an ultrasound observation apparatus capable of expanding a colored area of the elastic image while suppressing the influence on a color tone of the elastic image within the region of interest set by a user is provided.
