The present invention provides an electron gun which is excellent in voltage-resistant characteristics and has a first electrode less deformed, and a method of manufacturing the same. An electron gun according to the present invention is such one that includes a first electrode and other electrodes, in which electrodes excluding the first electrode and a holder for fitting an electrode are supported by an insulating supporter member. A first electrode structure into which the first electrode and a cathode are integrated with each other is fitted to the holder. This allows a deformation of the first electrode due to beading to be avoided. Moreover, because whole electrodes supported by the insulating supporter member can be washed before fitting the first electrode structure, it is possible to make an electron gun have excellent voltage-resistant characteristics.