To prevent reduction in quality of woven fabric by lessening response delay of detection of warp end breakage and suppressing advance of weaving in a state of warp end breakage as it is in detecting the warp end breakage by taking advantage of grasp of warp end breakage by a brush roller.

A brush roller 1 is rotatably installed with facing to a warp line and the brush roller 1 is positively rotated and driven in the direction of the warp line so as to bring the tip of brushes 16 into contact with the warp line. At least one pair of a projector 21 and a photodetector 22 are fixed and laid so that an optical axis 2 between them runs in parallel in the direction of the brush roller in a revolution zone of the brush roller 1. A warp detection period is fixed in a period in which the optical axis 2 does not interfere with the brushes 16. In a case in which the state of an optical axis screening signal outputted when the brushes 16 or the warp end breakage interferes with the optical axis 2 is judged by a warp end breakage decision device and is judged as the occurrence of the warp end breakage, the weaving machine is stopped.