A light regulator includes a substrate having an optical aperture, an even number of blade members (six or more) arranged substantially uniformly around the optical aperture, and spindles provided on the substrate for freely rotatably supporting base end portions of the blade members. The blade members are overlapped with each other at edges thereof, and tip portions thereof face the optical aperture. The blade members on the substrate are divided into a first blade set and a second blade set. The first blade set includes at least two first blade members overlapping with each other. The first blade members are rotatably supported at the base end portions thereof on the spindles, and tip portions of the first blades are placed inside an edge of the optical aperture when the first blades are fully closed.