A projector includes an integrator illumination optical system. The integrator illumination optical system includes: a first lens array having a plurality of first small lenses, a second lens having a plurality of second small lenses, and a polarization converter including: polarization separating layers. The second small lenses of the second lens array are each arranged with its convex surface oriented to the light-irradiation side. A light shield section is provided on a portion on an incident-side surface of the polarization converter, the portion excluding a light-incident surface corresponding to the polarization separating layers. An extending portion is formed on one of the second lens array and the polarization converter in a manner extending toward the other one of the second lens array and the polarization converter, the second lens array and the polarization converter bonded and fixed to each other by bonding and fixing the extending portion to the other one.