A head-up display system for a vehicle includes a front windshield, a display, a polarizing member and an optical rotatory film. The display for displaying an image on the front windshield to be viewed by a driver of the vehicle is disposed such that light therefrom is incident on the front windshield at an angle which is substantially equal to Brewster's angle. The polarizing member is disposed between the front windshield and the display for polarizing light from the display. The optical rotatory film serves to rotate the plane of polarization of light polarized by the polarizing member. The optical rotatory film installed on the front windshield includes a liquid crystal high polymer which is in twisted nematic orientation under liquid crystal condition and is in glassy condition at a temperature which is lower than liquid crystal transition point. Thus, double image problem can be eliminated with respect to light having a wide range of wavelengths.