To evaluate the excitability of the spinal motor neural function, the F-wave in evoked electromyogram is often used. As the dominant nerve to the muscle is electrically stimulated, retrograde action potentials are transmitted from the stimulation point to the anterior horn cells of the spinal cord. Action potentials that are regenerated in the anterior horn cells of the spinal cord are transmitted to the muscle in an anterograde manner, which are recorded in the muscle. Therefore, the F-wave is an indicator of the excitability of spinal motor nerve function. The F-wave is a complex action potential which is characterized that various waveforms can be recorded. Motor units of various sizes exist in the anterior horn cells of the spinal cord, and neurons are excited from small cell bodies to large cell bodies. It is a mechanism that the F-wave waveform differs depending on the size of neuron firing. There are few reports that focus on the shape of the waveform of the F-wave. For example, Suzuki et al. reported the analysis of an F-wave waveform measured from the thenar muscle of hemiplegic patients with cerebrovascular disorder by exercise therapy process. Their results showed that although no increase in amplitude was observed, waveform variety was recognized.