Herein we describe a rare fatal case of a novel bunyavirus-associated hemophagocytic lymphohistiocytosis (HLH) in a 62-year-old female patient. The novel bunyavirus infects patients with or without HLH who have similar clinical features such as fever, thrombocytopenia, and leukocytopenia. Therefore, the diagnosis of HLH can be easily missed. When HLH occurs, the disease worsens and the fatality rate rises. Our finding highlights the importance of bone marrow biopsy performed as soon as possible for patients suspected of having a novel bunyavirus infection and showing marked cytopenia in three cell lines.