Weft density and draw in plan play an important role since they affect physical properties such as fabric weight, cloth cover factor as well as seam strength. Weft density refers to the amount of weft yarn in one inch. Meanwhile, draw in plan refers to the amount of heald shaft used and the order of warp yarn through the heald. In this study, plain woven fabrics were produced by using Sulzer Rapier Loom Machine. There were two different types of weft density used which were 15 and 20 weft per centimeter (wpcm) and four draws in plan: pointed, straight, broken and broken mirror. Seams were constructed by using plain seam of Ssa-1, four stitches of stitch density and 301 lockstitches for stitch type. Subsequently, the fabric samples were tested on seam strength by using Testometric tester. As a result of this study, it is proven that weft density and draw in plan of woven plain fabric are parameters that affect the seam strength and seam efficiency. The highest increase in percentage of seam strength was obtained from straight draw in plan which increases up to 17.19% from 15wpcm to 20wpcm. Meanwhile, broken draw in plan has the lowest increase percentage for seam strength which is 6.46%. Furthermore, seam efficiency also shows straight draw in plan gives good fabric durability compared to others. Lastly, it also shows broken draw in plan has no significant effect on fabric tensile strength and seam strength.