Color cathode ray tube with in-line electron gun

A color cathode ray tube equipped with an in-line electron gun comprising three cathodes for emitting three electron beams of in-line arrangement toward a fluorescent screen, and a main lens for focusing said three electron beams on the fluorescent screen, said main lens comprising two cylindrical electrodes arranged in a spaced relationship in a direction of an axis of said tube, each having an opening and having therein a plate electrode with a beam passing area, said two cylindrical electrodes being given different voltages, wherein the D and S values are in the region where all of the following inequalities are satisfied;

• S<5.0,
• S<D, and
• 145.5.ltoreq.55S-20D
• S being a beam spacing in mm between central axes of said three adjacent electron beams, and D being the smaller dimension in mm of one of (a) a diameter in mm in a direction perpendicular to an in-line arrangement of said three electron beams of said cross section of an opening at opposing ends of said two cylindrical electrodes and (b) a distance in mm related to a spacing between a center of a side electron beam and a nearer inner edge of said two cylindrical electrodes in a direction of said in-line arrangement of said three electron beams of said cross section of the opening at opposing ends of said two cylindrical electrodes.