1. An object detection device for an area around a vehicle, comprising: an imaging device to capture a periphery of the vehicle as an image; and an image processing device to process an image of the periphery of the vehicle which is captured by the imaging device and then output a detection result, wherein the image processing device is comprised of: a detection area setting unit to set a plurality of detection areas of different sizes in the image of one frame; a plurality of area processing units to respectively carry out detection processing operations as to whether the object is present or absent simultaneously in parallel to each other by way of pattern matching in the plurality of the detection areas of different sizes that are set by the detection area setting unit; an integration processing unit to integrate and output a plurality of detection results that are respectively processed to be detected by the plurality of the area processing units, wherein: the plurality of detection areas of different sizes comprises a detection area of a large size and a detection area of a small size, and the detection area of the large size includes the detection area of the small size; and a white line detection processing unit to carry out detection processing of a white line of a road, wherein the detection area setting unit is configured to set the detection area of the large size and to set the detection area of the small size, according to the white line that is processed to be detected at the white line detection processing unit.