In a deflection yoke of self-convergence system for use with in-line type color picture tube, the intensity of a magnetic field, which causes the change in impedance of coils of saturable reactors respectively connected in series with two horizontal deflecting coils, is increased so that the variation rate of the inductance expressed in terms of a differential coefficient has the relationship of .theta.e/.theta.m.ltoreq.0.5 wherein .theta.m is a differential coefficient around the center of the picture where the degree of vertical deflection is very small and .theta.e is a differential coefficient at top and bottom sides of the picture where the degree of vertical deflection is maximum. In one embodiment, an auxiliary coil connected to the vertical deflection coils is employed in each of the saturable reactors so as to increase the intensity of the magnetic field applied to the saturable reactors. In another embodiment, metallic member(s) is/are arranged to be close to the saturable reactors so as to reduce reluctance.