PURPOSE: To restrict emission of secondary electrons in an anode by soldering metal such as titanium emitting few secondary electrons to an electron beam passing hole of the anode constituting an electron gun part.

CONSTITUTION: Metal, for example, titanium emitting few secondary electrons is soldered in the peripheral part of an electron beam passing hole 10 of an anode 5 in an electron gun part 1. Thereby, even when electron beam focusing is disturbed by a rising/falling characteristic of impressed voltage in the case of turning on/off an electric source in a microwave tube, and even if return electrons from a helical slow wave circuit unit 6 or the electrons incapable of focusing collide with the central part of the anode 5, metal such as titanium emitting not so much the secondary electrons is soldered in the peripheral part of the passing hole 10 situated in the central part of the anode 5, so that a plunge of the secondary electrons into the helical slow-wave circuit unit 6 can be restricted.