A microscopic change in structure of sound velocity or attenuation due to a pathological change can be grasped, the change being difficult to grasp with conventional measurement of an absolute value of sound velocity or attenuation. The above problem is solved by providing an ultrasound diagnostic device including an ultrasound probe including a plurality of ultrasound transducers transmitting ultrasound waves to an object and receiving ultrasound waves reflected from the object to output an ultrasound detection signal, a region-of-interest setting device setting a region of interest within the object, a transmission focus instructing device making the ultrasound probe transmit the ultrasound waves by focusing on the region of interest, a device setting at least one or more points of interest in the region of interest, a device finding a change in sound velocity or attenuation at the point of interest, and a device finding an index indicating a sonic variation or an attenuation variation based on the change in sound velocity or attenuation.
