The average patterns of equivalent ionospheric current system of polar magnetic storms (Dp-field) for both northern and southern polar regions are constructed by analyzing exactly simultaneous data in both polar regions during the IGY period. Those data of magnetic storms are classified into two groups; i.e., severe storm for which Kp=7.2 and moderate storm for which Kp=4.3. In both cases, the Dp patterns for the northern and southern polar regions are almost exactly symmetric with each other

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... th respect to the geomagnetic coordinates, suggesting that the geomagnetic conjugacy well holds between the two polar regions. Several remarks are made on mechanism of causation of the Dp field. It is emphasized, in particular, that the larger part of polar cap currents of the Dp field may be attributable to an enhancement of the Cqp field by a stronger solar wind.