An object detection device includes a raster scan execution unit that executes a raster scan on an input image using a scan window in order to detect an object within the input image which is input by an image input unit, a scan point acquisition unit that acquires scan points of the scan window which are positions on the input image during the execution of the raster scan, and a size-changing unit that changes a relative size of the input image with respect to the scan window. When the relative size is changed by the size-changing unit, an offset is given to the starting positions of the scan points after the change with respect to the starting positions of the scan points before the change.