Disclosed herein are an apparatus and a method for warning of vehicle collision. The positioning and state-reporting signal of a present vehicle is sensed and that of a target vehicle received. The signals are respectively converted to velocities. The relative velocity of the vehicles and the relative position of the vehicles after a time interval are obtained. The driver of the present vehicle is warned when the normal distance from the present vehicle to the line indicating the direction of the relative velocity is determined to be at a minimum and not greater than a warning distance.