The invention relates to an antifall device for a two-wheeled vehicle aimed at preventing the falling of the vehicle and its driver, when the rake angle reaches the limit angle corresponding to the limit of road holding of the tyres, for a given circular trajectory and a given road holding coefficient, whilst allowing the measurement of this limit angle. This objective has been achieved, according to the invention, by an antifall device (2) for a two-wheeled vehicle (1) equipped with tyres, the centre of gravity (G) of the vehicle moving over a circular trajectory of centre O and of radius R at a speed V, the mid plane (P) of the vehicle, containing the centre of gravity (G), forming together with the vertical plane (XZ) tangential to the trajectory a rake angle (C), the rake angle (C) increasing with the speed V of the vehicle and varying between a zero angle and a limit angle (C
lim ) beyond which there is a loss of transverse road holding of the tyres entailing the falling of the vehicle, the antifall device (2) being fixed laterally on the side of the vehicle interior to the trajectory and limiting the rake angle (C), when the speed V increases, to a maximum angle (C
max ) strictly greater than the limit angle (C
lim ), the antifall device (2) comprising a safety wheel (3) with centre (G
1 ), whose mid plane (P
1 ) cuts the mid plane (P) of the vehicle along a straight line situated above the ground and forming an angle (a) which differs from the maximum angle (C
max ) by at most 5°, a means of adjustment (4) of the maximum angle (C
max ) and a means of linking (5) between the safety wheel (3) and the vehicle (1).