Non-invasive device for locating a structure (N2), such as a nerve, in a region of a body having an external surface (Se), the device comprising: a focused ultrasonic transducer (1), advantageously of the HIFU type, designed to produce an ultrasound beam (Fu) through the external surface (Se) in the region, the beam (Fu) having a focal point that can be positioned on the structure (N2) monitoring means (3) for detecting a response of the structure when this is subjected to a stimulation and stimulation means (1 4) for stimulating the structure (N2), which delivers a response detected by the monitoring means (3), the stimulation means comprising the ultrasonic transducer (1) capable of delivering an ultrasound beam (Fu) to said structure (N2), so as to disturb it, characterized in that the device includes: an imager (2, 21, 22) mechanically coupled to the ultrasonic transducer (1) so that the imager follows the focal point of the transducer so as to display, on an image, the position of the focal point of the ultrasound beam (Fu) in said region of the body and marking means, for marking the position of the structure (N2) in the image produced by the imager.
