An object detecting device and an object detecting method capable of performing appropriate object detection that distinguishes an approaching moving object from a stationary object accurately. The relative velocity of an object, which exists in the lateral direction of a vehicle, with respect to the vehicle is detected, the absolute velocity of the object in the horizontal direction of the vehicle is calculated on the basis of the detection signal, and it is determined whether or not the object is an approaching moving object on the basis of the absolute velocity of the object in the horizontal direction of the vehicle. Accordingly, since it is possible to accurately distinguish whether an object existing in the lateral or oblique direction of the vehicle is an approaching moving object or a stationary object, it is possible to appropriately determine whether or not the object is an approaching moving object.