PURPOSE: To provide a semiconductor photo-electric cathode device wherein the quantum efficiency is improved, and the aperture ratio is 100%, the separation of picture elements in the structure is not required, and the modulation of a signal is made possible.

CONSTITUTION: A p-type first semiconductor layer 20 (light absorbing layer) for generating electrons by responding to incidence of light is formed on a semiconductor base plate 10. A p-type second semiconductor layer 30 (electron transferring layer) having the second impurity concentration if formed on the p-type semiconductor layer 20. A Schottky electrode 50 is in Schottky-contact with the p-type second semiconductor layer 30. A third semiconductor layer 40 (active layer) is formed on the front surface of the p-type second semiconductor layer 30 and also in the opening of the Schottky electrode 50. A semiconductor part 60 (channel lattice) having the second impurity concentration higher than that of the second semiconductor layer 30 is embedded in the p-type second semiconductor layer 30.