Nonobstetric vulvar hematomas are relatively uncommon compared with obstetric. They are often caused by traumatic vascular injury such as in cases of fall, coitus and sexual assault. There are no consensus guidelines for the appropriate initial treatment of conservative or surgical management. A 10-year-old premenarchal girl was admitted to emergency room for painful large vulvar hematoma. It was caused by a straddle bicycle accidents. An ultrasound and abdomen and pelvic computed tomography were done and a huge hematoma measuring in the vulva, labium, and perineum was shown, which was 11 x 9.7 x 7.7 cm sized hematoma with enhanced vessel meaning active arterial bleeding. Conservative management was recommended and ice packs were applied to the perineum. On admission day 5, necrotic change of left perineum was found. Surgical debridement with incision and drainage under general anesthesia was underwent. She subsequently showed no sign of complication and discharged on operation day 7. Conservative management is preferred for traumatic perineal hematoma in teenage girls, however, if the hematoma continues to grow or skin shows necrotic change surgical intervention may be required.