A 44-year-old woman had repeated bacterial infections because of hypoplastic myelodysplastic syndrome; therefore, she underwent allogeneic hematopoietic cell transplantation. Broad spectrum antibiotics were administered because she had bacterial infection and pneumonia 2 weeks before undergoing transplantation. On day19 after transplantation, she suddenly presented with hemoptysis. Stenotrophomonas maltophilia was considered to be the cause of hemorrhagic pneumonia, which required ventilation support, massive transfusion, and catecholamine administration. However, she died 8 h after the onset of hemoptysis. Severe S. maltophilia infections may occur in patients with immunocompromised conditions such as those after allogeneic hematopoietic cell transplantation.