Theoretical analysis which was derived in previous paper was applied to worsted and 100% polyester spun yarns for investigating its torsional behavior, and then compared and discussed with experimental results. Maximum yarn torsional rigidity was obtained with increasing yarn surface helix angle both theoretically and experimentally. However, the theoretical torsional rigidity of the spun yarn is explainable experimental result by considering the interfibre friction, and then it increases with the coefficient of interfibre friction.