The invention relates to a photocathode having a structure that permits a decrease in the radiant sensitivity at low temperatures is suppressed so that the S/N ratio is improved. In the photocathode, a light absorbing layer is formed on the upper layer of a substrate. An electron emitting layer is formed on the upper layer of the light absorbing layer. A contact layer having a striped-shape is formed on the upper layer of the electron emitting layer. A surface electrode composed of metal is formed on the surface of the contact layer. The interval between bars in the contact layer is adjusted so as to become 0.2 μm or more but 2 μm or less.