voice data phrase data sentence data and or sound data read from the information storage device 3 converting the synthesized voice sound data into an analog signal and supplying the resultant analog signal to a speaker in accordance with a voice sound output control signal supplied from the cpu the programs and data used in the navigation may be read from the outside via the information transmitter receiver unit 5 when the programs and data used in the navigation are read from the outside via the information transmitter receiver unit 5 a storage medium such as a dvd may be used instead of the cd rom as the information storage device 3 so that the programs and the data stored thereon can be updated to the latest versions the information storage device 3 may be omitted and the programs and the data may be directly stored in the flash memory or the ram in the central control unit 4 the operation of the navigation system is described below fig2 is a diagram showing a general flow of the processing performed by the navigation system according to the present embodiment of the invention in the navigation system constructed in the above described manner if the navigation guide system program is started by the cpu of the central control unit 4 the current location is detected by the current location detector 2 and a map around the current location is displayed step s 1 as shown in fig2 thereafter a destination is set based on a telephone number an address.