A vehicle speed while curving through steering maneuver is determined. A vehicle speed determination system is applicable to a vehicle having a front wheel and a rear wheel. The system includes: a wheel speed sensor configured to detect a wheel speed Vf of the front wheel; and an arithmetic circuit configured to determine a vehicle speed V(r) at a rear-wheel tangential point, based on a difference in vehicle speed between the front-wheel tangential point and the rear-wheel tangential point which occurs due to a difference between a locus of travel of the front wheel and a locus of travel of the rear wheel, and on the wheel speed Vf of the front wheel.