Testicular tumors are almost always malignant and shares 0.8~1.4% all malignancies. Meanwhile, interstitial cell tumor occurs in childhood, the sexual precocity is a main symptom due to androgen excess caused by hormonal inbalance. Recently, authors have experienced a case of interstitial cell tumor of testis which was proven by histologically in a 4yrs old male patient who complains voice change, sexual precocity, and painless mass on right testis with increased urinary 17-ketosteroid. And so, we present a case of interstitial cell tumor of testis with a brief review of literature.