A 67-year-old man had pain and swelling in the bilateral inguinal region. His past medical history included non-alcoholic steatohepatitis and liver cirrhosis. A clinical examination revealed a solid mass that was palpable along with the bilateral spermatic cord from the external inguinal ring to the root of the scrotum. Other than a hydrocele in the right testis, the epididymis and testes were intact. Abdominal computed tomography showed ascites and a solid tumor of the bilateral spermatic cord. Magnetic resonance imaging findings did not suggest malignancy, while antibiotics showed no effects. The patient wanted relief from the inguinal pain and a bilateral high orchiectomy was performed, during which time the spermatic cord was found firmly adhered to the surrounding tissue, and could not be completely resected. A histopathological examination showed epithelial mesothelioma. For additional examination of the ascites, the patient underwent paracentesis, which revealed an extremely high level of hyaluronic acid. Our working diagnosis was peritoneal malignant mesothelioma that had infiltrated the bilateral spermatic cord. We began systemic chemotherapy treatment with pemetrexed and cisplatin, but, the patient died 3 months after the operation.