Provided is an imaging element including a photoelectric conversion unit formed by stacking a first electrode, a photoelectric conversion layer and a second electrode. The photoelectric conversion unit further includes a charge storage electrode which is disposed to be spaced apart from the first electrode and disposed opposite to the photoelectric conversion layer via an insulating layer. The photoelectric conversion unit is formed of N number of photoelectric conversion unit segments, and the same applies to the photoelectric conversion layer, the insulating layer and the charge storage electrode. An n.sup.th photoelectric conversion unit segment is formed of an n.sup.th charge storage electrode segment, an n.sup.th insulating layer segment and an n.sup.th photoelectric conversion layer segment. As n increases, the n.sup.th photoelectric conversion unit segment is located farther from the first electrode. A thickness of the insulating layer segment gradually changes from a first to N.sup.th photoelectric conversion unit segment.