A deflection control apparatus is provided with: a controller programmed to: a determine whether or not a vehicle is about depart from a driving lane, perform a deflection control of supplying a brake fluid pressure to at least one of brake mechanisms provided for corresponding wheels so that a yaw moment in a direction of avoiding departure of the vehicle is applied to the vehicle, if it is determined that the vehicle is about to depart, arithmetically operate a departure angle of the vehicle, and arithmetically operate a boost trajectory for boosting the brake fluid pressure to a target brake fluid pressure on condition that the departure angle is greater than a predetermined angle. The controller is programmed to perform the deflection control after boosting in advance the brake fluid pressure associated with the at least one of the plurality of brake mechanism, on the basis of the boost trajectory.