The navigation device includes a detour exploring portion configured to explore a detour to avoid a section in which a traffic hazard occurs using map data at a level lower than a predetermined level when a traffic hazard determining portion determines that the traffic hazard occurs on the guidance route, and a display control portion configured to zoom the detour to match a scale of the detour to a currently designated scale, and synthesize and display the detour on a map image. The navigation device maintains the display of the wide area map and synthesizes and additionally displays a detour, for example, to pass through a road such as a narrow street included in a detailed map on the map image such that the user can receive, at a glance, a detour to easily bypass the section in which a traffic hazard occurs.