Series connected first to fourth reactor coils are wound on a core and connected in series with a horizontal deflection coil. A coil is also wound on the core and connected in series with a vertical deflection coil. The core is provided with two permanent magnets and magnetic bias is applied to the first to fourth reactor coils. A total inductance of first to fourth reactor coils is controlled by a vertical deflection current passing through the coil, and thereby, a correction amount of an amplitude of a horizontal deflection current is changed.