A map information assessment device has a processor configured to match a plurality of first zones representing a first road in a first map, with second zones representing a second road in a second map, the matching being made by using locations on the second road that are closest to the starting points of the first zones as the starting points, and using zones having the same lengths as the first zones, as the second zones corresponding to the first zones, to calculate zone adjacent distances between the end points of the second zones and the starting points of other second zones adjacent to those second zones, and to determine that positional information for the first road in a first zone is different from positional information for the second road in a second zone corresponding to that first zone, when the zone adjacent distance is greater than a threshold.