The present invention provides a lens array which is set to satisfy a preset relationship through setting the numerical values of lens array, row array, focal distance of lens, etc. in a lens assembly which is arranged by a plurality of lens. The lens array includes a plurality of lens assembly members with a plurality of lenses and a light blocking member with a plurality of apertures arranged therein. The lens assembly members are arranged so that an optical axis of each of the lenses of one of the lens assembly members is aligned with an optical axis of each of the lenses of another of the lens assembly members. Further, the lens assembly members and the light blocking member are arranged so that the following relationship is satisfied: where PY is a pitch of the lenses in one row, PX is a pitch of the rows, F is a focal length of each of the lenses, LO is a distance between each of the lenses and an object surface thereof, and RA is a distance between the optical axis and an inner surface of the aperture.