A cathode ray tube which is equipped with an electron gun (K) having a construction capable of not only improving the focusing characteristics for the entire region of a screen (14) and for the total current range of an electron beam (10) without any supply of a dynamic focusing voltage to achieve a satisfactory resolution, but also reducing the Moire phenomena in a low current range. Also disclosed is a method of correcting the deflection aberration of the cathode tube. A deflection aberration according to the deflection of the electron beam (10) is corrected by establishing a fixed inhomogeneous electric field, which has its equipotential lines narrowed in interval the more for the longer distance from the axis of symmetry of an electric field.