1. A vehicle periphery monitoring device comprising: an image capturing unit mounted on a vehicle and configured to acquire a captured image around a periphery of the vehicle by performing image capturing while the vehicle is traveling; an identification target area determiner configured to determine identification target areas from within an image area in the captured image acquired by the image capturing unit; and an object identifier configured to identify whether or not an object exists within the identification target areas determined by the identification target area determiner, wherein: the object identifier includes a first identifying unit for which a computation amount thereof required by an identification process for identifying the object is relatively small, and a second identifying unit for which a computation amount thereof required by an identification process for identifying the object is relatively large; and the identification target area determiner determines at least one of the identification target areas to be subjected to the identification process by the second identifying unit, by performing a clustering process in relation to position and/or scale with respect to plural area candidates extracted by the first identifying unit as areas in which the object exists.