Abstract: A navigation device including a display configured to display map information indicating a traveling route of a vehicle including the navigation device, a memory configured to store a plurality of sound source files for providing aural information adapted to represent directional changes to be made by the vehicle in accordance with the displayed map information, and a controller configured to check the map information and determine a directional change the vehicle is to make in the traveling route of the vehicle, to search the memory for a sound source file corresponding to the determined directional change the vehicle is to make, and to output the sound source file at a preset time before the directional change is to be made to inform a driver of the vehicle about what directional change is upcoming.