The object-detection device for vehicle provides a transmission-and-reception device; a reflection point calculation device; a segment setting device; a median point calculation device; and a relative speed calculation device, wherein the relative speed calculation device eliminates a calculation result of the relative speed in the car width direction, with respect to the reflection points calculated based on the electromagnetic waves which are irradiated to the most downward direction in the specified angle in the vertical direction, in case that the number of difference between the reflection points in the current processing and the reflection points in the previous processing is equal to or greater than a predetermined number.