To provide a simple technique to accurately associate positional relation between image information acquired from a sensor for visible light and image information acquired from a sensor for infrared light.

This is a position adjusting method between a visible light image from a photographic film acquired by the sensor for visible light, and an infrared light image from the photographic film acquired by the sensor for infrared light. The visible light image and the infrared light image are divided into a plurality of regions, a plurality times of position shifts are conducted for each corresponding region, a pattern matching process is conducted between the visible light image and the infrared light image in each shifted position, and the shifted position, whose conformity is highest, is considered to be a right positional relation of the visible light image and the infrared light image.