A vehicle operation assisting system includes an assist yaw rate calculator which calculates an assist yaw rate necessary to avoid an obstacle based on a detection result of the obstacle by a radar device, an actual vehicle moving amount calculator which calculates an actual vehicle moving amount from a yaw rate and a lateral acceleration of a vehicle. When an avoiding operation detector determines an avoiding operation of a driver, a target vehicle moving amount setting device replaces a standard moving amount based on an avoiding operation of a driver with the assist yaw rate, and a vehicle movement controller controls lateral movement of the vehicle so that the actual vehicle moving amount agrees with the assist yaw rate. At this time, in addition to the yaw rate, the lateral acceleration is also used for calculating the actual vehicle moving amount, and therefore an upset of the vehicle behavior can be avoided by properly controlling the lateral movement of the vehicle on a road having a low friction coefficient on which the tires easily skid. A vehicle operation assisting system capable of properly performing an obstacle avoiding operation and a restoring operation even on a road having a low friction coefficient is thereby provided.