Performing map construction under a crowded environment where there are a lot of people. It includes a successive image acquisition unit that obtains images that are taken while a robot is moving, a local feature quantity extraction unit that extracts a quantity at each feature point from the images, a feature quantity matching unit that performs matching among the quantities in the input images, where quantities are extracted by the extraction unit, an invariant feature quantity calculation unit that calculates an average of the matched quantities among a predetermined number of images by the matching unit as an invariant feature quantity, a distance information acquisition unit that calculates distance information corresponding to each invariant feature quantity based on a position of the robot at times when the images are obtained, and a map generation unit that generates a local metrical map as a hybrid map.