An object of the present invention is to provide a map creation system and a map creating method capable of accurately creating road data on map data used for estimating a road being travelled by a vehicle. A map creation system includes a trajectory data creation unit creating trajectory data of a vehicle travelling in a predetermined area on a first road on the basis of positional information of the vehicle, a representative point extraction unit extracting, of created plural pieces of the trajectory data, representative points located on a side of a second road different from the first road, and a road data creation unit creating data for the first road on map data on the basis of the plural representative points extracted for respective plural predetermined areas.