Abstract: To provide an electron source which is suitable for an electron beam lithography machine, an Auger electron spectroscope or the like and provides a small total emission current even in a high angular intensity operation. An electron gun provided with a cathode which comprises a single crystal needle of tungsten or molybdenum and a coating layer consisting of oxygen and at least one metal element selected from the group consisting of Group 2A, Group 3A and Group 4A, formed on its surface, characterized in that an apex of the cathode as a truncated cone shape, and the truncated cone shape portion has a cone angle of from 25° to 95° and a diameter of the top surface of from 5 ?m to 200 ?m.