Brake control apparatus for four wheel drive vehicles

A vehicle is equipped with a coupling such as, for example, a center differential (3) or a variable clutch (90), that transmits a driving force from an engine (1) to a front-wheel drive shaft (4F) and a rear-wheel drive shaft (4R) while allowing a difference in rotational speed therebetween and a brake controller (50) that individually controls braking forces to be applied to wheels in accordance with a running state of the vehicle. A vehicular brake controller (50, S210) prohibits braking force control from being started if the coupling is in its locked state or when the coupling causes a relatively great connecting strength to exist between the fron-wheel and rear-wheel drive shafts. While braking force control is being performed by the brake controller (50), braking force control is continued even if there is a command to cause the coupling to be locked or to achieve the great coupling strength.