A solid-state image pickup element includes: a semiconductor layer of a first conductivity type; a pixel area having pixels formed in a matrix form, each of the pixels including a photoelectric conversion element having a pn junction formed of the semiconductor layer of the first conductivity type and a first semiconductor region of a second conductivity type, a second semiconductor region of the first conductivity type formed on a first surface side of the semiconductor layer, and potential control wiring connected electrically to the second semiconductor region; and a pixel signal readout circuit including at least one MOS transistor formed on the first surface side of the semiconductor layer in the pixel area to have a source and a drain formed of an impurity region of the second conductivity type. Incidence of light to the photoelectric conversion element is made from a second surface side opposite to the first surface side.