An aperture unit (20) comprises an aperture cover (22), an aperture base (27), and a light shielding portion (24). The aperture cover (22) has an opening (22a) through which light passes. The aperture base (27) is disposed on the downstream side of the aperture cover (22) in the light incidence direction, and has an opening (27a) through which light passes. The light shielding portion (24) is disposed between the aperture cover (22) and the aperture base (27), and has an opening (24d) through which the light that passed through the opening (22a) passes, and a plurality of opaque aperture stop blades (24a, 24b, 24c) that are formed from a polyimide resin and vary the size of the opening (24d).