A 59-year-old woman presented with a 2-month history of headache with left eyelid swelling, and erythema in her lower extremities. She also had persistent low-grade fever and weight loss of 3 kg over 2 months. Blood biochemistry tests performed elsewhere indicated an inflammatory reaction. One week before hospitalization, she was treated at our hospital using the Japanese herbal medicines, keishito and shosaikoto. On hospitalization, her headache and eyelid swelling had slightly decreased ; therefore, she was advised to continue the Japanese herbal medicine, shosaikoto. Contrast-enhanced brain MRI showed meningeal thickening extending from the right anterior cranial fossa to the left cavernous sinus, suggesting a diagnosis of hypertrophic pachymeningitis. Cerebrospinal fluid examination revealed mild pleocytosis with mononuclear leukocyte predominance. Biopsy of the erythematous lesion on her leg was carried out, and analysis of the obtained specimen led to the diagnosis of erythema nodosum. In this case, exhaustive efforts to identify the cause of the combined hypertrophic pachymeningitis and erythema nodosum were unsuccessful. However, the symptoms and signs were alleviated after treatment with the Japanese herbal medicine, shosaikoto. We did not administer steroid therapy, which is generally prescribed for such an immune-inflammatory disease, because of the possible presence of an infectious disease. The Japanese herbal medicine was found to be a candidate therapeutic agent in this case.