PURPOSE: To judge a cornering limit with high accuracy at the time of moderate steering, and transmit the vehicle condition of the cornering limit to a driver without any interference onto steering.

CONSTITUTION: A self aligning torque detection means M1 detects the self aligning torque of a steering wheel. A lateral force detection means M2 detects the lateral force of a wheel. A judgment means M4 obtains the reference value of self aligning torque corresponding to detected lateral force, based on a relation between the lateral force and the self aligning torque preset in a mapping means M3, and compares it with detected self aligning torque for the judgment of a cornering limit.