PURPOSE: To prevent the breakage of support bars buried with mixed electrode groups made of materials with different thermal expansion coefficients due to the heat history by making the burial width of other electrodes smaller than that of the electrode support pieces of electrodes made of a relatively low-thermal expansion material.

CONSTITUTION: An electron gun electrode structure 20 is constituted of three cathode structures 20B (20A, 20C) and G1WG4 electrodes 21W24, the electrodes are buried in two insulator support bars 17 arranged with electrode support pieces 25 and auxiliary support pieces 26 formed integrally, and they are fixed at the preset distance. The G1, G2 electrodes 21, 22 are made of a low-thermal expansion material (e.g., 42 alloy), and the other electrodes are made of a stainless material. The burial width l2 of other electrodes is set smaller than that l1 of the electrode support pieces 25 of the G1, G2 electrodes 21, 22. The uniform stress is applied to the support bars 17 and the breakage of the support bars 17 due to the heat history is prevented because l2 is smaller than l1 even if the electrodes G1, G2 21, 22 are thermally expanded during the operation of a cathode-ray tube.