An alert ECU acquires intersection information representing a situation of an intersection (target intersection) where a host vehicle will enter. The alert ECU excludes the leftward and rightward orientations from assistance-target orientations when the target intersection is grade separated, when a traffic light is installed at the target intersection, when a median strip is installed in the target intersection along the host vehicle traveling direction, or when a stop sign is not installed at the target intersection. As a result, an alert to a driver for a target vehicle is inhibited when the target vehicle is approaching the host vehicle from an orientation in which it is estimated that the target vehicle cannot collide with the host vehicle and when the target vehicle is approaching the host vehicle from an orientation in which it is estimated that the target vehicle will not collide with the host vehicle for regulatory reasons.