A 33-year-old man visited our hospital complaining of painless left scrotal swelling. Serum alphafetoprotein (AFP) and human chorionic gonadotropin-beta (HCG-β) were within normal range. Computed tomography revealed a heterogeneous tumor in the left scrotum and para-aortic lymph node swelling. We diagnosed the tumor as stage IIA testicular cancer and performed left high inguinal orchiectomy. Histopathological diagnosis was mature teratoma with no associated malignant germ cell tumor. The patient was followed-up without adjuvant chemotherapy because the size of para-aortic lymph nodes was remarkably reduced one month after the orchiectomy. The patient must be followed up carefully for possible metastasis.