A color cathode ray tube has a phosphor screen and an in-line electron gun. Each of the focus electrode and the anode of has a single opening for passing three electron beams. The single opening has a diameter larger in a horizontal direction than a diameter thereof in a vertical direction. Each of the focus electrode and the anode has a plate electrode placed therein and forming apertures for passing the three electron beams respectively. The focus electrode and the anode forms a main lens therebetween. The distance from the main lens to the phosphor screen is 360 mm or less, the outside diameter T in mm of the neck portion of the evacuated envelope housing the electron gun satisfies 23.5 mm.ltoreq.T.ltoreq.25.3 mm, the value D in mm of twice the distance from the center of a trajectory of a side electron beam to a vertical edge of the single opening in each of the focus electrode and the anode satisfies 6.5 mm