A braking force control system in a vehicle includes rotational speed sensors for detecting rotational speeds of front wheels and rear wheels, respectively, and braking force regulating devices capable of individually regulating braking forces for the front and rear wheels. In the braking force control system, the following two controls (1) and (2) are carried out: a front/rear braking force distribution control (1) for controlling the distribution of braking forces to front and rear wheel sides, such that a difference between front and rear wheel speeds is equalized to a target value; and an antilock brake control (2) for determining wheel locking tendencies individually in the front wheel side and the rear wheel side and controlling the braking force for the wheel determined to be in the locking tendency. When the antilock brake control is started in one of the front wheel side and the rear wheel side during execution of the front/rear braking force distribution control, the braking force distribution control is discontinued in the other of the front wheel side and the rear wheel side to increase the braking force of the other side at a defined increase rate. Thus, both of the braking force distribution control and the antilock control are feasible together and moreover, the switching-over between these controls can be smoothly achieved.