To study spinal neuron excitability during relaxation imagery, we studied F-waves using the relaxation period of hold-relax. [Subjects] Twenty-six healthy volunteers (21.5 ± 2.0 years) participated in this study. [Methods] F-waves were recorded in a resting position and during relaxation imagery using hold-relax. They were recorded at 0, 5, 10, and 15 min of the relaxation imagery period. We analyzed persistence, the F/M amplitude ratio, and latency of the recorded F-waves. [Results] The F/M amplitude ratio and F-wave frequency did not differ significantly between the resting and relaxation imagery conditions; however, F-wave persistence after 15 min of relaxation imagery was significantly lower than that at rest. [Conclusion] Relaxation imagery can decrease spinal nerve excitability.