Polarizing split layers 26 and reflection layers 27 are provided on bonding surfaces between prism rods 24a and 24b. Polarization conversion devices 25 are bonded to an emission surface from which linearly polarized light being reflected by the polarizing split layers 26 and reflected by the reflection layer 27 are emitted. The polarization conversion devices 25 are formed by bonding plural prism rods 30 with side surfaces being inclined by 45° with respect to an incidence surface. Retardation films formed of dielectric multilayers are provided between the bonding surfaces to give a phase difference of a ½wavelength to transmitted light. The retardation films and bonding borderlines 31 are inclined by 45° within a plane perpendicular to an optical axis of linearly polarized light so that an optical axis of the retardation film has an angle of 45° with respect to a polarization direction of the linearly polarized light.