1. A vehicle comprising: an imaging means; an image capturing means which captures a color image of a road via the imaging means; an area extraction means which extracts areas having a similar color feature value from the captured color image of the road captured by the image capturing means; a white balance processing means which performs, for each of the extracted areas extracted by the area extraction means, a white balance process of correcting each pixel data in the extracted area so as to reduce the degree of divergence in the level between color components according to a level balance between the color components of the pixel data in the extracted area; and a road sign detection means which detects a road sign on the road from the color image subjected to the white balance process.