Member having antireflection structure

A reflection of unnecessary light, which should be prevented, can be suppressed, and occurrence of stray light can be reduced using a member having an antireflection structure, comprising a plate-like portion , and an aperture portion formed in the plate-like portion , wherein the antireflection structure having an aspect ratio of or more and comprising structural elements arranged in an array form at a period smaller than the shortest wavelength of light, the reflection of which should be prevented, is formed on an inner wall of the aperture portion