A 32-year-old primigravid woman developed acquired factor VIII inhibitor after delivery. She presented with postpartum hemorrhage and large hematoma in episiotomy site. Laboratory examinations showed markedly prolonged activated partial thromboplastin time, low levels of factor VIII (8%), and factor VIII inhibitor (2 Bethesda units). The bleeding was controlled successfully using combined treatment with factor VIII, intravenous immunoglobulin, steroids, and recombinant factor VIIa. Six months after delivery, factor VIII inhibitor was not present and factor VIII concentration increased to normal range. Acquired hemophilia is a life-threatening disorder. Precise screening of coagulation factors is essential for diagnosis of persisting postpartum hemorrhage.