A display system 1 is composed of a ghost image reducing device 100 and an image device 10. The ghost image reducing device 100 comprises an image reflecting element 110 and a polarizing element 120. The image reflecting element 110 includes a substrate 112 and a phase modulating element 114 which is adjacent to the substrate 112 and has a reflecting surface 114a. The image device 10 generates a polarized image light P1 which is received by the reflecting surface 114a. Then, a portion of the polarized image light P1 is reflected by the reflecting surface 114a for producing a first reflecting polarized image light P2, another portion of the polarized light P1 is projected into the phase modulating element 114 and reflected by the substrate 112 for producing a second reflecting polarized image light S2 whose polarizing direction is different from that of the first reflecting polarized image light P2.