PURPOSE: To provide the title method intended to eliminate the non-uniform elongation and/or tension variation of warps, so designed that when the operation halt of a loom is sensed, a leveling motor for heald frames is started, and when the respective tops of said frames come to nearly the same level, the motor is halted.

CONSTITUTION: When a switch PS detects the operation halt of a loom, a leveling motor M for heald frames is started, a leveling driving shaft S is revolved through a speed reducer to drive an opening device 4, thus making a leveling for the heald frames. The operation of the motor M is halted when a control section C determines that the respective tops of the heald frames come to a nearly the same level through signals from position detection switches LS1, LS2,....