The present invention relates to a robotic device (2) for positioning a surgical instrument relative to the body (1) of a patient, comprising a first robotic arm (3) equipped at one end with securing means with at least one surgical instrument , so as to maintain, move, position and guide said surgical instrument； means for anatomically resetting said first arm relative to said body (1), said registration being carried out by registration of an image of an area of the anatomy of said patient acquired peroperatively with respect to previously acquired imaging； sensors for detecting in real time the internal movements of said anatomical zone and means for compensating displacements of said first arm as a function of said detected movements. Such a device is characterized in that it comprises at least a second robotic arm (4) equipped at one end of said detection sensors of said internal movements of the anatomical area, said detection sensors being positioned at said contact of said anatomical area； means for controlling the positioning of said first arm (3) relative to, on the one hand, said captured internal movements and, on the other hand, with respect to the external movements induced to said second arm (4).La présente invention concerne un dispositif robotique (2) de positionnement d'instrument chirurgical par rapport au corps (1) d'un patient, comprenant un premier bras robotisé (3) équipé à une extrémité de moyens de solidarisation avec au moins un instrument chirurgical, de manière à maintenir, déplacer, positionner et guider ledit instrument chirurgical ； des moyens de recalage anatomique dudit premier bras par rapport audit corps (1), ledit recalage s'effectuant par recalage d'une image d'une zone de l'anatomie dudit patient acquise en per-opératoire par rapport à une imagerie acquise préalablement ； des capteurs de détection en temps réel des mouvements internes de ladite zone anatomique et des moyens de compensation des déplacements dudit premier bras en
