A solid image pickup apparatus which is not easily susceptible to an influence of an emitted light caused by impact ionization. The solid image pickup apparatus of the present invention includes an output circuit for converting a signal charge outputted from a photoelectric converter into an analog signal and outputting the signal. The output circuit includes a charge-voltage converter for converting the charge transferred from the photoelectric converter into a voltage signal, a plurality of source follower circuits for performing impedance conversion, and a reverse amplification circuit. A gate length of a MOSFET constituting the final-stage source follower circuit in the output circuit is longer than the gate length of the MOSFET of another source follower circuit or the like. Therefore, impact ionization does not occur in a position in which the impact ionization most easily occurs, the emitted light caused by the impact ionization does not enter the photoelectric converter, and an image quality can be prevented from being deteriorated.