[Purpose] Gait training that increases non-paretic step length in stroke patients increases the propulsive force of the paretic leg. However, it limits knee flexion during the swing phase of gait, and this may cause gait disturbances such as worsening of gait pattern and increased risk of falling. Therefore, this study aimed to investigate the effects of increasing non-paretic step length on the joint movement and muscle activity of a paretic lower limb during hemiparetic gait. [Participants and Methods] A total of 15 hemiparetic patients with chronic stroke were enrolled in this study. Spatiotemporal parameters, along with kinematic and electromyography data of their paretic lower limbs, were measured during a 10-m distance overground walking. Two walking conditions were assessed: normal (comfortable gait) and non-paretic-long (gait with increased non-paretic step length) conditions. [Results] Under the non-paretic-long condition, the trailing limb angle was larger than under the normal condition. However, no significant difference was observed in the knee flexion angle during the swing phase. [Conclusion] Increasing non-paretic step length during gait is unlikely to limit knee flexion during the swing phase and can safely improve the propulsive force of a paretic leg.