The present invention relates to a method for managing map data for a vehicle using a navigation system, wherein upon display of the map data, memory loading for the display of the map data can be quickly performed by reducing the number of access to a physical storage medium with an entire map stored therein.To this end, when a travel guide map is generated again based on a new location as the position of a vehicle varies, only a certain number of map segments are retrieved from a physical storage medium such as a CD-ROM to generate the travel guide map, thereby making map-displaying speed faster. Further, when the travel guide map is generated again based on the new location as the position of the vehicle varies, map data loading speed can be faster by preventing reusable map segments among map segments loaded on an operation memory from being unnecessarily deleted, retrieved again from the physical storage medium and inserted into the operation memory.