To solve a problem that flat yarns used as wefts are collapsed not to give a sufficient woven fabric, when opened yarns are woven with a loom having a conventional reed, whereby a beating function must be achieved by one or more other methods, and a problem that, when opened yarns not having sufficient stability in the lateral direction are used as wefts, a special device for constantly controlling the density of the wefts, namely distances between the wefts, is needed.

A controller comprising servomotors and a CPU is used in connection with an opening movement in one cycle for producing the woven fabric, thereby performing normal and reverse rotation movements for feeding and winding operations, achieving the beating function and the density- controlling function, and realizing a high speed operation and a low cost production. Further, the width of the weft is measured with an optical sensor, and a feeding rate and a winding rate are corrected on the basis of the measurement result to reduce the error of the density.