1. An object detection device for area around 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; and 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.