PURPOSE: To obtain high resolution over the whole area of the phosphor screen surface by applying the voltage resistor-divided by the first and second resistors respectively to the first and second focusing electrodes.

CONSTITUTION: The first resistor 71 applied with the voltage higher than the preset focusing voltage and the second resistor 72 applied with the voltage higher than the preset focusing voltage and the dynamic voltage increased or decreased synchronously with the deflecting current on both ends are provided, the voltage resistor-divided by the first resistor 71 is applied to the first focusing electrode 4, the voltage resistor-divided by the second resistor 72 is applied to the second focusing electrode 5. Only one high voltage is fed through the base pin of a picture tube, the fed dynamic voltage is a low DC potential, the deflection aberration caused by the nonuniformity of the deflection magnetic field and the deflection aberration caused by the long and large orbit of an electron beam due to the increase of the deflection quantity can be eliminated by applying the dynamic voltage with the low DC potential. Good resolution can be thereby obtained over the whole area of a phosphor screen surface.