An obstacle detection system for vehicles detects kinetic attributes relative to a vehicle equipped with the system of an object present in a forward path of travel of the vehicle, sets a presumed zone into which the object is expected to have entered at a lapse of a specified period based on the kinetic attributes, and proves an object detected at a lapse of the specified period as the object previously detected if the object of second detection is determined as one having moved into the presumed zone and an obstacle precarious to the vehicle.