Metastatic tumors of the tunica vaginalis testis from gastric cancer are extremely rare. We report here on a case of a 48-year-old man who had undergone total gastrectomy due to advanced gastric cancer 23 months previously, and he presented with right painless scrotal swelling. A hard mass was palpated along the right spermatic cord and there was an associated hydrocele around the mass. Ultrasonography showed homegenous hypoechoic lesions in the spermatic cord and anechoic lesion superior to the right testis, which was suggestive of hydrocele of the testis. Exploration was performed via inguinal incision. Multiple hemorrhagic small nodules were noted on the surface of the tunica vaginalis. Also, a tumor in the spermatic cord was present beyond the inner inguinal ring. On microscopic examination, adenocarcinoma cell nests, which were consistent with primary gastric cancer, were found in the tunica vaginalis testis, spermatic cord and peritesticular soft tissue, but not within the parenchyme of the testis or epididymis.