The effect of the mechanical properties of sewing threads on the seam pucker of wool fabric has been studied. The results of the theoretical and experimental study of the structural jamming showed that the effect of structural jamming on the seam pucker is minimal. Among the mechanical properties of sewing thread, the initial modulus and the residual strain after 7th cycle of extension/relaxation had significant effect on the seam pucker. High sewing thread tension resulted in severe seam pucker after sewing.