We calculated the effective mass of ring-torsion (RT) and bond-order (BO) defect states in a pernigraniline-base polymer, on the basis of an extended Ginder-Epstein model. The calculated effective mass is sensitive to electron-RT coupling. In the case of medium coupling, the effective mass for an RT-BO soliton is≈650me and that for an RT-BO polaron is≈178me. RT relaxation dominates the defect mass. The large effective masses imply that linear translation of the defects is not likely to be a dominant mechanism of charge transport in the polymer.