[Purpose] To investigate the effects of long-term body-weight-supported treadmill training on walking ability and physical function in an elderly individual with incomplete cervical spinal cord injury. [Participant and Methods] The patient was a 68 year-old male with an incomplete spinal cord injury at the C3/C4 level, incurred when he was 56 years old. He initiated home-based body-weight-supported treadmill training using a body-weight-supported treadmill installed at his home. His walking ability was measured as the percentage of body weight load reduction, and his physical function was evaluated using manual muscle testing and measuement of the range of motion of his lower limbs. [Results] The physical function of the lower limbs was improved, maintained, or showed delayed decline until 9.5 years post-injury. [Conclusion] Long-term body-weight-supported treadmill training may improve, maintain, or at least delay the decline of the physical function of participants for several years, without causing any remarkable complications.