Acquired hemophilia A (AHA) is a rare hemorrhagic disorder caused by autoantibodies against factor VIII (FVIII). An 80-year-old woman presented multiple bruises on her upper and lower extremities, along with gross hematuria. Extensive ecchymosis and swelling were observed on the buttocks. She had anemia and normal platelet count. The initial coagulation results showed prolonged activated partial thromboplastin time (aPTT, 68.5 seconds) and normal prothrombin time. According to the mixing test, we observed a decreased FVIII activity (2%), increased factor VIII inhibitor (FVIII-I) titer (74.4 BU), and negative lupus anticoagulant. AHA was diagnosed based on late onset bleeding and increased FVIII-I titer. Additionally, she met the criteria for systemic lupus erythematosus (oral ulcer, photosensitivity, renal disorder, and positivity for antinuclear and anti-β2-glycoprotein-I antibodies). She was started on oral prednisolone for FVIII-I eradication. Post-treatment, her bleeding tendency, aPTT (47.3 seconds), and FVIII-I titer decreased (1.24 BU), and FVIII activity increased (10%).