A lane deviation avoidance system for an adaptive cruise control system equipped vehicle includes an electronic control unit that executes a host vehicle's lane deviation avoidance control in which a change in vehicle dynamic behavior occurs in a direction that avoids the host vehicle from deviating from a driving lane when there is a possibility of the host vehicle's lane deviation from the driving lane. The control unit puts a priority on the lane deviation avoidance control by limiting a driving force acting on the host vehicle, when there is the possibility of the host vehicle's lane deviation from the driving lane.