PURPOSE: To improve the reliability of the titled mechanism by restraining the energy consumed by non-linear resistors thereby extending the life of non- linear resistors by a method wherein parallel circuits comprising capacitors and resistors are series-connected to non-linear resistors of tap selective circuits.

CONSTITUTION: Within an on-load tap changer provided with a transformer 1 with two or more taps and a pair of thyristors 52, 53; 62, 63 parallel-connected to one another in the reverse direction as well as two sets or more tap selective circuits 50, 60 comprising non-linear resistors 51, 61 parallel-connected to said pair of thyristors, the parallel circuits of condensers 55, 65 and resistors 54, 64 are series-connected to non-linear resistors 51, 61 of tap selective circuits 50, 60. The resistors 54, 64 are parallel-connected to the capacitors 55, 65 to discharge the charge accumulated in the capacitors 55, 65 resultantly the time constant of discharge is selected notably longer than the time required for a series of tap change-over operations. Through these procedures, any voltage increased by impedance of inter tap winding can be compensated by the capacitors 55, 65 to restrict the limited voltage of non-linear resistors to low level thereby restraining the energy consumed by the non-linear resistors.