Multi-focusing type electron gun for color cathode ray tubes

In a multi-focusing type electron gun having an electrode assembly for focusing electron beams, the assembly comprising first through eighth electrodes in order starting from a cathode and having a shield cup, wherein the third, fourth, and fifth electrodes form a first unipotential lens, the fifth, six, and seventh electrodes form a second unipotential lens, and the seventh and eighth electrodes form a bipotential lens, the improvement wherein the sixth electrode comprises a primary electrode on a side facing the fifth electrode and a secondary electrode on a side facing the seventh electrode, the primary and secondary electrodes each having three apertures formed therein, the three apertures of the primary electrode being aligned with the three apertures of the secondary electrode, and the three apertures comprise a central aperture and two lateral apertures, the central aperture of the primary electrode having a larger diameter than a diameter of the lateral apertures thereof, and equal to a diameter of the lateral apertures of the secondary electrode, and the central aperture of the secondary electrode having a comparatively smaller diameter than the diameter of the lateral apertures thereof and equal to the diameter of the lateral apertures of the primary electrode, such that a voltage difference of the second unipotential lens becomes uniform to thereby obtain an expanded focus lens.