There is provided a lens array and an lens array capable of suitably preventing irregular brightness without reducing resolution. A microlens array 20 of a screen 2 includes upper-level microlenses 21H and lower-level microlenses 21L which are formed on the incidence surface of the screen 2, which have the same effective diameter, and which have a structure that generates an optical path length difference Δ in transmission light. By disposing the upper-level microlenses 21H and the lower-level microlenses 21L at an interval based on the effective diameter, the basic periodic structure of a lens period PL is formed. Further, the upper-level microlenses 21H and the lower-level microlenses 21L form a basic block comprising a combination of the lenses having a structure that generates the optical path length difference. A concave-and-convex period PC based on the basic block is an integer multiple of the lens period PL.