Vehicle running state detecting device

A vehicle driving condition detection device is adapted to detect a vehicle running along a banked or laterally sloping road, as well as a lateral acceleration, and sideslip angle with good accuracy. The sideslip angle is estimated at a vehicle-body sideslip angle estimating circuit based on a steering angle deltaf, a lateral acceleration y, a yaw rate {dot over (theta)}, and a vehicle speed V. In addition, using a differentiating device, the estimated sideslip angle is differentiated to calculate a slip angular velocity. A subtracting device is provided at which a deviation is calculated between the slip angular velocity and a slip angular velocity detected at a slip angular velocity calculating circuit. The deviation can detect a banked or laterally sloping road due to the fact that the detected slip angular velocity at the slip angular velocity calculating circuit includes the gravity acceleration component that depends on the slope or bank of the road. Upon detecting a banked or sloping road, a deviation DELTAy (={dot over (theta)}.V-y) is outputted from a switching device, and at a subtracting device the detected lateral acceleration y is corrected by being subtracted with the deviation DELTAy. On the basis of the resultant or corrected lateral acceleration y, the vehicle-body sideslip angle is estimated. Such an estimation is made irrespective of the slope or bank of the road.