Abstract: An optical system is provided for use in a vehicle head-up display including a display panel for displaying drive information image, a backlight unit for irradiating light toward the display panel and an optical system for adjusting the size and focal distance of the drive information image projected from the display panel toward a windshield of a motor vehicle. The optical system includes a pre-lens reflection mirror array for reflecting the drive information image projected from the display panel to travel along a first roundabout path, a lens array for adjusting the size and focal distance of the drive information image reflected by the pre-lens reflection mirror array, and a post-lens reflection mirror array for reflecting the drive information image coming from the display panel toward the windshield to travel along a second roundabout path.