A transmission mode photocathode 2 comprises: an optically transparent substrate 4 having an outside face 4a to which light is incident, and an inside face 4b from which the light incident to the outside face 4a side is output; a photoelectric conversion layer 5 disposed on the inside face 4b side of the optically transparent substrate 4 and configured to convert the light output from the inside face 4b into a photoelectron or photoelectrons; and an optically-transparent electroconductive layer 6 comprising graphene, and disposed between the optically transparent substrate 4 and the photoelectric conversion layer 5.