To diminish and correct the rotation unbalance and reduce the reed beating vibration by freely changing and regulating the attached position of a counterweight attached to a rocking shaft according to a bias in a centrifugal load caused by a change in a width size of a reed.

This mechanism for regulating a counterweight position in a reed beating vibration damping apparatus comprises a rocking shaft 2 of a loom for supporting constituent members of a reed beating system and causing reed beating operations, and a correcting counterweight 34 attached to a part of an area for changing the reed end centrifugal load on at least the side opposite to the yarn feed of the shaft 2 so as to enable the free positional regulation and capable of diminishing the rotation unbalance of a weight bias caused by a change in reed width size by changing and regulating the attached position thereof.