1. A map database generating system for generating a map database, the map database including a road network comprising a plurality of nodes having position information and a link connecting two of the nodes, and road attribute information associated with the road network, the system comprising: a non-transitory memory including a feature database that stores feature information relating to features existing on a road and on a periphery of the road, each piece of feature information being associated with a unique identification symbol, each piece of feature information including: disposition information expressing a spatial disposition of the feature independently of the road network; form information that defines a physical form of the feature as the feature exists on or adjacent to the road; accuracy information expressing an accuracy of the feature information; and acquisition timing information expressing an acquisition timing of the feature information; wherein identification symbols having at least one part in common are allocated to feature information relating to an identical feature in the feature database; and a processor that is programmed to: output the feature information stored in the feature database; input map information constituting the map database, the map information being generated based on the output feature information; detect a presence of plural feature information relating to an identical feature but having different accuracy information from the feature database, the detection being made based on the acquisition timing information and at least one of the identification symbol, the disposition information, and the form information of each piece of feature information; and select feature information having an accuracy required to generate the map information as the feature information to be output, the selection being made on the basis of the accuracy information included in each piece of detected feature information.