A case of testicular torsion in a neonate is reported. A two-day-old boy with an abnormal hard mass in the right scrotum was referred to us. Right testicular torsion was suspected and operation was performed at 13 days after birth. During the operation extra-vaginal torsion of the right spermatic cord was revealed. The right testis appeared extensively necrotic, and right orchiectomy was selected. Histological examination revealed massively coagulo-necrotic testicular structure. To our knowledge, this is the 56th case of testicular torsion in a neonate reported in Japan. We discussed the onset, laterality, form, direction, angle and treatment of the torsion.