A solid-state imaging element according to the present disclosure includes one or more photoelectric conversion layers, a penetrating electrode, and a connection pad. The one or more photoelectric conversion layers are provided on one principal surface side serving as a light incidence plane of a semiconductor substrate. The penetrating electrode is provided in a pixel area, connected at one end to the photoelectric conversion layer to penetrate through front and back surfaces of the semiconductor substrate, and transfers an electric charge photoelectrically converted by the photoelectric conversion layer, to a different principal surface side of the semiconductor substrate. The connection pad is provided on a same layer as gates (Ga, Gr, G1, and g2) of transistors (AMP, RST, TG1, and TG2) provided on the different principal surface side of the semiconductor substrate, and to which a different end of the penetrating electrode is connected.