PURPOSE: To assemble an electron gun with few defects such as a mismatch due to deformation of an electrode main body and fluctuation of cutoff voltage. CONSTITUTION: Bead glasses 18 each provided with a recessed part 18a are made to approach an electrode 15 from both sides thereof, and stopped at the time when pins 16 of the electrode 15 are positioned inside of the recessed parts 18a of the bead glasses 18. Both side parts of each of the recessed parts 18a of the bead glasses 18 are wrappingly nipped by nipping members 23 to be deformed so as to approach each other. As a result, both side parts of each of the recessed parts 18a of the bead glasses 18 nip opposing faces of a plate- like pin 16. Accordingly, pressing force from the bead glass 18 is received only by pins 16 and not applied to a main body of the electrode 15 through the pins 16 so that deformation of the main body of the electrode 15 can be avoided.