PURPOSE: To selectively attain high sensitivity by providing a silver layer made of a granular material at least partially having the grain size of 80-150nm and layers made of silver oxide, potassium, and cesium formed on the silver layer.

CONSTITUTION: A silver layer 22 made of a granular material having the grain size of 60-150nm partially including at least the grain size of 80-150nm, a silver oxide layer 23, a potassium slayer 24, and a cesium layer 25 are deposited in sequence on a glass substrate 21. When light is fed into the substrate 21 of this transmission type photoelectric surface, photoelectrons are generated and emitted into vacuum from the cesium layer 25. A photoelectric tube is provided with a bottomed cylindrical airtight container, and the airtight container is made of glass. The light receiving face portion of the airtight container forms the glass substrate 21. High sensitivity is selectively attained in the infrared region near the wavelength of 1.5μm, thus this can be widely utilized for inspecting an optical communication system.