To achieve cost reduction of an opening/closing member of a blind, a screen, a curtain, or the like, which opens/closes an opening of a window, a skylight window, or the like, in a building such as a house, an office, or a hospital.

At least one of an operating cord 1 for use in any one of opening/closing members A to D, such as a Venetian blind, a pleated curtain, a Roman shade, and a longitudinal blind, for opening/closing the same, an elevating cord 3 for elevating slats 2, 12, a screen 7 or a curtain 10, a bottom cord 13 for connecting lower edges of the respective slats 12 of the longitudinal blind, is formed of a longitudinally knitted cord E. The longitudinally knitted cord E is formed by inserting core strings 22 into the center of side strings 21 which are obtained by sequentially knitting loops 23 formed of a plurality of strings 21a, and therefore the cord E is high in flexibility and strength.