1. An object detection device for detecting an object in an image, comprising: a plurality of processor units each configured to refer to an image and perform detection processing to detect an object included in the image; a division unit configured to divide an image into N divided images, each having an overlapping portion with at least another one of the divided images, in order for each of the plurality of processor units to perform the detection processing independently; and a transfer unit configured to transfer the divided images divided by the division unit to the plurality of processor units, each of the processor units performing the detection processing by referring to a transferred image transferred thereto by the transfer unit, and the division unit determining the number N of divided images in accordance with a data amount of the overlapping portion in each divided image to be transferred by the transfer unit and with a processing load for the detection processing to be performed by each of the plurality of processor units.