Steering wheel mounted anti-theft device

Anti-theft device (2) for vehicles that can be coupled to a steering wheel, comprising an elongated body provided with means for being secured to the rim (10) of the steering wheel, constituted by a primary part (4) with first (12) and second (14) means able to engage with respective diametrically opposite portions of the rim (10) of the steering wheel, and a secondary part (6) able to make the primary part (4) longer for preventing the rotation of said steering wheel; the primary part (4) and the secondary part (6) are hinged between them so that the secondary part (6) can rotate with respect to the primary part (4) on a plane substantially parallel to the plane of the rim (10) of the steering wheel, for assuming a working position wherein the two parts (4, 6) are substantially aligned.