An imaging element comprises: an optical element substrate part in which the imaging element generates a signal charge by photo-electrically converting an incident light applied from one surface side of the optical element substrate part to read the signal charge from the other surface side of the optical element substrate part and picks up an image; and a CMOS circuit substrate part connected to the other surface side of the optical element substrate part so as to transfer the signal charge generated in the photoelectric conversion layer, wherein the optical element substrate part comprises: a photoelectric conversion layer to generate the signal charge by photo-electrically converting the incident light; a charge storage part that stores the signal charge; and a reading transistor that reads the signal charge stored in the charge storage part.