We report a patient, who had neuropathic pain after radiation, called “chronic post-radiation pain syndrome,” who was successfully treated by Shimbuto. The patient was a 83-year-old man, diagnosed with Stage IB non-small cell lung cancer of the left upper lobe. Although the lesion had a surgical indication, he selected radiotherapy, and stereotactic body radiotherapy was performed. A few months later, he experienced neuropathic pain in his anterolateral chest wall. Loxoprofen and acetaminophen had little effect; moreover, tramadol hydrochloride/acetaminophen combination tablets and pregabalin induced drowsiness and dizziness. He then wanted to take Kampo medicine (Japanese traditional medicine) and was observed to have susceptibility to gastrointestinal disorders and cold intolerance by Kampo diagnosis. We prescribed Shimbuto 5 g per day, along with pregabalin. After 2 months, the pain had almost disappeared and he could stop taking pregabalin. Shimbuto is usually prescribed to patients at a risk of gastrointestinal disorders, pain, numbness, and other symptoms induced by cold intolerance. Shimbuto includes the extract of processed aconite root, which is effective for pain and numbness; therefore, it might be a good option for treating neuropathic pain when we have difficulties with Western medicine.