PURPOSE: To shorten working hours and to reduce the number of workers in the case of the restretching work of a trolley wire.

CONSTITUTION: The one end of an old trolley wire dropped down on the ground is fixed to a drum 10, and a motor 2 is driven by a generator 4 to rotate the drum 10 for winding the trolley wire in order. Since a truck is movable on a rail, a winding device A itself is travelled on the rail by winding the trolley wire. Since the old trolley wire is thereby wound on the drum and removed, the cutting work of the trolley wire and its loading work on the truck become unnecessary to sharply reduce the number of workers and shorten working hours. In addition, the safety of the work is improved.