A head up display for a vehicle according to an embodiment includes a display panel configured to emit an image light; a polarized light plate configured to make the image light emitted from the display linearly polarized; a reflective mirror configured to reflect the image light onto a windshield of a vehicle; a polarized light reflective mirror configured to be disposed to face the reflective mirror; and a phase delay mirror configured to convert a phase of the light inputted from the polarized light plate and reflect the converted phase to the polarized light reflective mirror, and to convert a phase of the light reflected from the polarized light reflective mirror and reflect the converted phase to the polarized light reflective mirror, thereby minimizing a width in the forward and backward direction.