A color cathode ray tube equipped with an in-line electron gun for emitting three electron beams includes a main lens made up of two cylindrical electrodes arranged in a spaced relationship. Each of the electrodes has an opening and having therein a plate electrode with a beam passing area. The electrodes are given different voltages, wherein D and S have values in a region where all of the following inequalities are satisfied;S.ltoreq.5.0S