Disclosed are an ultrasound diagnosis device and an ultrasound diagnosis method which make it possible to capture micro-structural changes in sound velocity/attenuation caused by pathological changes, said micro-structural changes being difficult to capture in conventional measurement of the absolute values of sound velocity/attenuation. The ultrasound diagnosis device is provided with: an ultrasound probe including a plurality of ultrasound wave transducers for transmitting ultrasound waves to a subject and also for receiving ultrasound waves reflected by the subject to thereby output an ultrasound detection signal a region-of-interest setting device for setting a region of interest in the subject a transmission focus instruction device for, with respect to the ultrasound probe, focusing transmission of ultrasound waves in the region of interest a device for setting at least one or more focus points in the region of interest a device for obtaining changes in sound velocity or attenuation at the focus point(s) and a device for obtaining indices which indicate sound velocity fluctuations or attenuation fluctuations, the indices being obtained in accordance with the changes in sound velocity or attenuation.Linvention concerne un dispositif de diagnostic par ultrasons et un procédé de diagnostic par ultrasons qui permettent de capter des changements micro-structurels de la vitesse/latténuation du son du fait de changements pathologiques, lesquels changements micro-structurels sont difficiles à capter lors de la mesure traditionnelle des valeurs absolues de vitesse/atténuation du son. Le dispositif de diagnostic par ultrasons comprend : une sonde à ultrasons comprenant plusieurs transducteurs dondes ultrasoniques afin de transmettre des ondes ultrasoniques vers un sujet et afin de recevoir des ondes ultrasoniques réfléchies par le sujet de manière à émettre un signal de détection ultrasonique un dispositif de choix de zone dintérêt pour choisir une zone dintérêt chez l
