Disclosed are collision preventing apparatuses and methods for a vehicle. The collision preventing apparatus estimate whether objects located in a vicinity of the vehicle may collide with each other based on data collected from a sensor in the vehicle, determine a trajectory of each of the objects, verify whether the estimated trajectories intersect, determine that the objects may collide with each other in response to the estimated trajectories overlapping, inform each of the objects of a collision risk when the objects may collide with each other, and differently perform an operation of informing the objects of the collision risk based on a collision level of each of the objects.