VEHICLE TURN CHARACTERISTICS ESTIMATION APPARATUS

A turning-characteristic estimating unit 11 of an ECU 1 estimates a stability factor Kh and a steering-response time constant coefficient Tp that are parameter values related to turning characteristics of a vehicle 10. A standard yaw rate YrStd of the vehicle 10 is calculated using the estimation values of the stability factor Kh and the steering-response time constant coefficient Tp estimated by the turning-characteristic estimating unit 11. A validity determining unit 12 of the ECU 1 determines the validity of the estimation values based on the standard yaw rate YrStd and an actual yaw rate Yr of the vehicle 10. This allows improving the estimation accuracy of the stability factor Kh and the steering-response time constant coefficient Tp.