An ultrasound observation device includes a processor configured to execute: generating an ultrasound image； setting at least two regions of interest on the ultrasound image； calculating feature value on each of the set regions based on the ultrasound signal； calculating a representative value on each of the set regions based on the calculated feature value of each of the set regions； selecting at least one representative value from the representatives values of the set regions； selecting the feature value having a predetermined relationship with the selected representatives value from the feature value used for calculating the selected representatives value； setting the selected feature value as a threshold； setting, as a display specification, a color pattern of the feature value to be displayed on a display based on the set threshold； and generating feature-value image data in which the feature value is colored with the set display specification.
