Abstract: A homogenizer includes a convex-lens array pair including a first convex-lens array disposed on a light entrance side and a second convex-lens array disposed on a light emission side. The first convex-lens array and the second convex-lens array are disposed so as to face each other such that each of the convex-lens arrays has a lens surface opposed to each other outward or inward. The first convex-lens array includes a plurality of first convex lenses in an array arrangement. The second convex-lens array includes a plurality of second convex lenses in an array arrangement. The first convex lens has an average internal transmission angle for incident light entering a lens-surface center region in the lens cross-section and being in parallel with the symmetry axis being equal to or more than 1.3 times an average internal transmission angle of a spherical convex lens.