PURPOSE: To supply completely processed yarns to a weaving machine and prevent occurrence of defects of a fabric by starting the weaving machine after attainment of a weft-processing machine to a steady operation state and removing weft before the starting of the weaving machine as waste yarns.

CONSTITUTION: After a prescribed period from starting of a weft-processing machine 5 when a steady operation state is attained, a weaving machine 1 is started. Weft supplied from the weft-processing machine 5 before the starting of the weaving machine 1 is removed as waste yarns so that completely processed yarns may be supplied to the weaving machine 1, thus preventing occurrence of defects of a fabric. In addition, a cutter 45 for cutting weft (Y) is attached to the outlet of an injection nozzle 4 and the resultant waste weft yarns are removed by suction using a waste yarn-removing pipe 46.