PURPOSE: To provide an improving method of a magnetostriction characteristic of a deflection yoke, in which high magnetostriction characteristic is simply obtained at the design stage of the deflection yoke, and the cost of the deflection yoke is reduced by decreasing the number of magnets.

CONSTITUTION: Auxiliary magnetic field generating means 15, 16 positioned on the rear side of a deflection yoke 10 mounted onto a color picture tube, in which three electron guns B, G, R are horizontally arranged in a raw and no field controller exists on the inside, and perpendicularly crossed to the arranging direction of the electron guns to increase the sensibility of beams from the electron gun G in the center by applying a magnetic field produced by vertical deflection current or correcting current synchronized with the deflection current to beams by the electron gun are installed on the same level as the arranging direction of the electron guns to improve a magnetostriction characteristic of the deflection yoke 10. The auxiliary magnetic field generating means 17, 18 are reversely corrected to frame correction to strengthen the their functions.