The invention concerns an anti-theft device for locking a steering column of a motor vehicle. The anti-theft device comprises: a locking bolt (2) that is axially mobile between an unlocked position away from a steering column and a locked position in which it blocks the rotation of said column, a rotary cam (3) for actuating the axial movement of the locking bolt (2), said rotary cam (3) comprising a toothed wheel (6) intended to be driven in rotation, characterised in that the rotary cam (3) comprises an elastic return means (9; 16) of which a first end is secured to the toothed wheel (6) and a second free end (9b; 16b) projects radially from the toothed wheel (6) and engages with a locking counter-form (15) provided in the locking bolt (2) in order to block the axial movement of the locking bolt (2) against the elastic return of same (5) to the locked position.