A navigation apparatus is provided for ensuring safe execution of a navigation function even when a vehicle travels high altitude areas. The navigation apparatus has a function of searching for a route to a destination, and comprises the following structure: a memory device 30 for storing map data or the like, a data memory 70 for being capable of storing part of the map data or the like stored in the memory device 30, a position detector 500 for detecting positional information on a vehicle position, a controller 80 for causing the map data stored in the memory device 30 to be stored in a backup memory area 74 of the data memory 70 when the vehicle reaches a predetermined altitude based on the positional information, and a display controller 50 for displaying the map data read from the data memory 70 on a display device 51.