To guide a vehicle to a route which is irradiated by much solar light at the time of guiding a route for a vehicle.

The navigation ECU 10 of a route guiding device for a vehicle retrieves a route leading to the destination by using map data for search stored in a map database 14, and displays it on a display 16 for guiding a vehicle. When the terminal voltage of a battery 24 for storing the power of a solar battery 22 becomes lower, the navigation ECU 10 guides the vehicle by researching a route with a large solar irradiation intensity. This research is executed by cost arithmetic operation with the level of solar irradiation as sunshine costs. The sunshine costs are calculated according to an object near a link and time.