Abstract: An electron gun for a color cathode ray tube includes a triode having a cathode, a control electrode, and a screen electrode for producing electron beams; first, second, and third focus electrodes; and a final accelerating electrode sequentially disposed from the screen electrode. A first constant voltage is applied to the screen electrode and the second focus electrode, a second constant voltage higher than the first constant voltage is applied to the first focus electrode and the third focus electrode, and an anode voltage higher than the second constant voltage is applied to the final accelerating electrode, so that electron beams cross from the triode cross between a main lens formed by the third focus electrode and the final accelerating electrode, and an auxiliary lens formed by the first, second, and third focus electrodes. The electron gun produces uniform size electron beam spots over a fluorescent film of a cathode ray tube with reduced spherical aberration.