Driving assistance device

In a driving assistance device which uses a simple system configuration to superimpose a guidance image onto an image captured by a vehicle mounted camera so as to alleviate the operational burden of a driver, an image of the surroundings of the vehicle captured by the vehicle mounted camera is displayed in an in-vehicle display device as a display image superimposed with a guide image employing a guide display, that is, a graphic image containing guiding lines. Predicted course lines, which are guiding lines indicating on the captured image a predicted course based on the actual steering angle of the vehicle, are stored in a storage unit for storing graphic images forming guide displays, as a plurality of graphic images which are generated every predetermined steering angle. A graphic image of predicted course lines is acquired from the storage unit according to the actual steering angle of the vehicle, and is provided as a guide image.