A display unit displays supplied image information on or through a front glass of a vehicle. A system controller generates and supplies the image information to the display unit. The image information indicates lane guides of the traveling lane, which correspond to a configuration of a traveling lane that is viewed from a view point position of a driver through the front glass. The system controller sets a display color of the lane guides displayed by the display unit to a color, which is distinguishable from a color of a road surface.