1. An ultrasonic observation apparatus that transmits an ultrasonic wave to a specimen and receives the ultrasonic wave reflected from the specimen, the ultrasonic observation apparatus comprising: a region of interest setting unit that is able to set information on a position, and a size in a depth direction, of a region of interest in the specimen; a focus point calculation unit that divides the region of interest into a plurality of partial regions of interest according to the number of focus points in the region of interest, the number of focus points being a parameter associated with size information of the region of interest set by the region of interest setting unit, calculates a focus point in each of the partial regions of interest, and determines a transmission timing according to the calculated focus point; a transmitting and receiving unit that performs a transmission-and-reception of an ultrasonic wave on a sound ray in the region of interest as many times as the number of focus points on the sound ray, the transmission-and-reception of the ultrasonic wave being focused on the focus point calculated by the focus point calculation unit; a frequency analysis unit that calculates a plurality of frequency spectra by analyzing the ultrasonic wave received by the transmitting and receiving unit with reference to the focus point; a feature data extracting unit that extracts feature data of the frequency spectra calculated by the frequency analysis unit by approximating the frequency spectra; and an image processing unit that generates ultrasonic image data having a display mode corresponding to the feature data extracted by the feature data extracting unit, wherein the focus point calculation unit sets a focus point for a B-mode image for displaying brightness converted from amplitude of the ultrasonic wave reflected from the specimen, and does not set a focus point according to the number of focus points in the partial regions of interest including the focus point for the B-mode image.