Provided is a fat diagnosis ancillary device capable of accurately performing heating and fat diagnosis at the same measurement position so that there is a match between the position and direction of irradiation of ultrasound for image diagnosis and the position and direction of irradiation light for heating, the ancillary device being retrofitted to an ultrasonic diagnosis device. A fat diagnosis system (A) comprising an ultrasonic diagnosis device (1) for acquiring an echo signal by a main probe (2) and performing image diagnosis, and a fat diagnosis ancillary device (10) for performing fat diagnosis, wherein the fat diagnosis ancillary device is configured to include: a subsidiary probe (4) capable of emitting at least ultrasound or light for heating a probe holder (5) for causing the ultrasound emitted from the main probe and the ultrasound or light emitted from the subsidiary probe to be beamed from a common beaming port so that the respective axial directions match and a fat information calculation unit (12) for calculating fat information including the change in ultrasound velocity from the echo signals before and after heating, measured using the main probe and the subsidiary probe.La présente invention concerne un dispositif auxiliaire de diagnostic de graisse apte à mettre en œuvre de façon précise un chauffage et un diagnostic de graisse au niveau dune même position de mesure, de sorte quil existe une correspondance entre la position et la direction dexposition à des ultrasons aux fins de diagnostic par imagerie et la position et la direction dexposition à une lumière aux fins de chauffage, le dispositif auxiliaire étant monté en rattrapage sur un dispositif de diagnostic à ultrasons. Un système (A) de diagnostic de graisse comprend un dispositif de diagnostic à ultrasons (1) destiné à acquérir un signal décho à laide dune sonde principale (2) et à mettre en œuvre un diagnostic par imagerie, ainsi quun dispositif auxiliaire (10) de diagnostic de graisse d
