1. A navigation device which displays, on a screen, a route guidance object indicating a route along which an own a vehicle is to travel, the navigation device comprising: an image pickup section that obtains a photographed image ahead of a vehicle; a white line detection section that detects a white line on a road in the photographed image; a map information storage section that stores map information including road shape data which represents a road shape; a road shape data correction section that corrects the road shape data, based on a detection result of the white line on the road; a route guidance object generation section that generates the route guidance object having a shape in alignment with a road which corresponds to an optimum route searching by a route search section, based on the corrected road shape data; and a display section that displays the generated route guidance object so as to be superimposed on the photographed image, the road shape data is a set of road shape points, and the road shape data correction section generates a first road shape vector along the white line on the road detected by the white line detection section, draws a perpendicular line from one of the road shape points toward the road shape vector, and sets an intersection point of the road shape vector with the perpendicular line as a corrected road shape point so as to correct the road shape data.