PURPOSE: To prevent the signal charge from being left half stored in one read and eliminate the residual image on the image pickup screen due to the excessive signal charge, by connecting a diode, which has a function to clip the potential of a diode for signal storage, to the diode for signal storage in a photodetecting part.

CONSTITUTION: A row of photodetectors a1∼an consisting of signal charge storage diodes, where a photoconductor film for conversion from an optical signal to an electric signal is formed in a solid-state image pickup device and the optical signal charge generated in this photoconductor film is stored, and a row of photodetectors b1∼bn which read in the charge from a row of photodetectors a1∼an and transfer the charge vertically in the direction of a code PT are provided. A diffusion layer 15 forming the second diode which has the conduction type opposite to that of the first diode part 1 is provided in the first diode part 1 of a row of photodetectors a1∼an in this constitution and is insulated from a metallic electrode 2 of the diode part 1 and is connected to a polysilicon electrode 16 by a contact part 17. An optical voltage is applied to the diffusion layer through the electrode 16 to clip the potential of the diode part 1, thus preventing the signal charge from being left half stored.