A technique is proposed for enabling stable detection of an object even when the contrast of an image is lowered overall or partially.A preprocessing section 12 is added to the upstream stage of an object detecting processing section 13, and provides an obtained corrected image (image obtained by subjecting an input image to contrast enhancement) as an input image for the object detecting processing section 13. This facilitates the detection of the object even when the contrast of the entire screen is lowered due to fog or rain. Furthermore, the object detecting processing section 13 detects the object by using not only the corrected image from the preprocessing section 12 but also correction characteristic information 23 containing image characteristics regarding the correction (contrast enhancement). This attempts to reduce an influence of noises enhanced by the contrast enhancement.