To improve efficiency of re-wiring work of an electric-car wire by simultaneously proceeding collection and wire-extension work of the electric-car wire.

A first working car 2 equipped with a suspension wire winding machine 7, a second working car 3 loading a trolley wire winding machine 8, a third working car 4 equipped with a suspension wire delivery machine 9 and a fourth working car 5 equipped with a trolley wire delivery machine 10 are sequentially aligned and arranged on a roadway R under a re-wiring objective electric-car wire. An old suspension wire M1 and an old trolley wire T1 from which supporting metal fittings, etc. are previously removed are sequentially wound up by the winding machines 7, 8 and collected while these working cars 2, 3, 4, 5 are almost simultaneously moved. Simultaneously, a new suspension wire M2 and a new trolley wire T2 are delivered and extended by the delivery machines 9, 10, mounted with the supporting metal fittings, etc. and fixed. It is possible to improve efficiency of the work as a series of these collection and extension work is continuously and almost simultaneously carried out.