A system for acquiring map information reliably even when a vehicle is running in a blind area where the map information is not acquirable in real time, assisting the vehicle to keep running smoothly. In this system, necessary map information can be acquired from an external information center upon request via a communication device. Specifying data of a blind area in which the map information is not acquirable in real time is previously stored in a memory. Based on the specifying data stored in the memory and a current position of the vehicle detected as by GPS, a processor acquires the map information of the blind area from the information center upon request when the vehicle approaches the blind area. The acquired map information is stored in the memory and is read out for use in navigation.