Factors affecting fabric quality are yarn, weaving machine and men. Among them the weaving machine and men can be controlled in the weaving Process. Most of fabric defects result from the yarn, the weak points of which cause the discontinuities in the machine operation responsible for the endbreakages. The interruption in production can be reduced by an optimal operation of weaving machines, but the cause of endbreakages can not be completely eliminated. The places where the machine stopped and restarted leave streaks on the fabrics, which result in the fabric defects. These defects, so called stop marks, lead to the irregularity of weft density This paper deals with relationship between the change in weft density and the weaving interruption. The weft density change, the stop mark, was measured in terms of pickspacing and the mode of weaving interruption determined by applying different forms of speed variations. The results show that the weft density change is mostly influenced by the rate of speed variation. The initial loading on the warp yarns is independent of the total weft density change, but it is responsible for the distribution of the weft density irregularity.