Abstract: In-line type electron gun in a color cathode ray tube including a pre-focusing lens part having at least two electrodes for focusing electron beams, a main lens part having two, or more than two electrodes for focusing the electron beams onto a screen, and at least one electrostatic field controlling electrode in the electrodes of the main lens part having a center electron beam pass through hole and two outer electron beam pass through holes, wherein each of the outer electron beam pass through holes has a form a circular hole and a rectangular hole are combined therein, the rectangular hole having a height ‘V2’ greater than a vertical diameter ‘V1’ of the center beam pass through hole of the electrostatic field controlling electrode, thereby permitting an excellent focusing and improving assembly work.