PURPOSE: To restrain leakage magnetic fields using the deflecting yoke in different types of display units by switching a tap provided in a cancel coil.

CONSTITUTION: A deflection yoke 11 provided with tapped cancel coils 2 is attached to a display unit. As to the number of turns in each coil 2 the tap of each coil 2 is switched by a switching device 3 so that a leakage magnetic field from a horizontally deflecting coil 1 is minimized and that the strength of a canceling magnetic field from each coil 2 is regulated. An optimum number of turns in each coil 2 depending on conditions can be obtained. When the strength of the leakage magnetic field generated around the display unit is not uniform, the tap is switched so that the number of turns in the upper coil 2 is greater than that of the lower coil 1 thereby uniformly reducing the leakage magnetic field around the unit to a small one.