An object detection device for a vehicle includes a transmitting-receiving unit, a reflection point computation unit, an object width computation unit, a representative point setting unit, a lateral relative velocity computation unit, a memory unit, and a lateral relative velocity correction unit. The transmitting-receiving unit transmits an electromagnetic wave. The object width computation unit computes a width of the object. The lateral relative velocity computation unit computes a lateral relative velocity. The memory unit records the object as a width-widening static object when the object is a static object and an amount of increase in the width of the object is greater than a predetermined value, based on a detection history of the object detected at each of the predetermined cycle. The lateral relative velocity correction unit corrects the lateral relative velocity, when the object recorded as the width-widening static object is detected at a left end part or a right end part of a detection region.