PURPOSE: To match the axis of an anode electrode and a shield cap accurately, by providing a frange section on the anode electrode while forming positioning means on said frange section and the bottom face of a shield cap.

CONSTITUTION: There holes 21 arranged on a line for passing three electron beams and four small holes 22 placed at the positions departed by same distance from the center are provided on the bottom face of a shield cap 20. A frange section 27 is provided while adjoining to the rising section 25 of G4 cap constituting an anode electrode, then four small holes 28 are made at the positions on the frange section 26 corresponding with said small hole 22. When assembling the shield cap 20 and the G4 cap 24, a guide pin is inserted through the small holes 22 and 28 to coincide thier axis. Consequently the central axis of the shield cap and the anode electrode can be coincided easily with high accuracy.