PURPOSE: To prevent the abrasion of an extension cord by winding two extension cords to hold the constant posture of an operation rail for opening and closing a net, in such state as not coming in contact with each other during a travel in directions opposite to each other, regarding a wire screen where a net is freely opened and closed like an accordion.

CONSTITUTION: One end of a net 2 is made free to contract and expand like an accordion via many pleats, and fixed to one side rail 13 of a wire screen frame 1. Also, an operation rail 16 for open/close operation is fixed to the other end of the net 2. An extension cord 3 with one end connected to the upper section of the one side rail 13 of the frame 1 is inserted from the upper end to the lower end of the rail 16, and jointed to the lower section of the other side rail 14. Also, another extension cord 4 with one end fitted to the lower end of the rail 16 is extended along deflectors 23 and 24 under the one side rail 13, and led to the upper end of the other side rail 14 via the inside of the frame 1. Then, the cord 4 is wound around a deflector 26 and jointed to the upper end of the rail 16. The parallel travel mechanism of the rail 16 is constituted of the cords 3 and 4.