An imaging element array includes a plurality of imaging elements that are arranged side by side. Each imaging element is integrally molded as a single piece element and includes an incident surface, an emission surface, and a plurality of reflective surfaces which are provided between the incident surface and the emission surface. The imaging element includes a first reflective element and propagation preventing surfaces. The first reflective element includes at least one of the plurality of reflective surfaces and has an effective region which is in contact with adjacent imaging elements. The propagation preventing surfaces are to either side of another one of the plurality of reflective surfaces and are positioned to prevent light rays other than light rays reflected from the reflective surface from propagating to the emission surface.