Vehicle behavior control device

A vehicle behavior control device for controlling acceleration/deceleration includes: a velocity acquisition device; a current position acquisition device; a preceding vehicle determination device; a following distance detection device; a preceding vehicle information acquisition device; a relative velocity calculation device of a preceding vehicle; a first evaluation index calculation device of a first evaluation index indicating an approaching/separating state to the preceding vehicle in view of the preceding vehicle velocity; a first deceleration target determination device for determining whether the first evaluation index exceeds a first deceleration threshold; and a following deceleration calculation device for calculating a first required deceleration when the first evaluation index exceeds the first deceleration threshold. The first required deceleration provides to match an actual relative velocity with a first target relative velocity, which is determined based on the first evaluation index and the following distance.