1. An ultrasound diagnosis apparatus comprising: an image processing unit by which when a first region of interest that is a region of interest when displaying onto a certain display unit an ultrasound image created based on a reflected wave of an ultrasound wave transmitted to a subject from an ultrasound probe, and a second region of interest that is a region of interest overlapping with the first region of interest and for observing a certain subject portion included in the ultrasound image, as well as a projecting direction, are received from a certain input unit, a first image is created by performing volume rendering processing on an ultrasound image in the first region of interest onto a projective plane along the projecting direction, and a second image on which motion of the certain subject portion can be identified is created from an ultrasound image in the second region of interest; and a system control unit that controls processing so as to display the first image and the second image created by the image processing unit in a superimposed manner onto the certain display unit.