The case was a 28-year-old Japanese female who was considered to be infected with malaria in India. She manifested fever in Tokyo, Japan, and was brought to Toho University Hospital due to continuous high fever and severe thrombocytopenia. Ring forms at 11% of her RBCs and ICT^TM Malaria P. f/P. v test was also positive for Plasmodium falciparum diagnosis. Not only the high parasitemia and delay of the diagnosis (6 days after the onset of fever), but also her DIC status required prompt and proper treatment. The diagnosis of severe malaria was strongly considered, and intravenous Artesunate (a qinghaosu derivative) was decided to be administered to the patient. After the four series of administration, mefloquine was subsequently given to prevent recrudescence. Parasite clearance time and fever clearance time were 24 hours and 108 hours, respectively. Thrombocytopenia was improved shortly after the treatment, but then anemia was once worsened with following gradual improvement. No other significant side effects were observed and no recrudescence occurred up to 8 months after her discharge. In Japan, very few cases treated with intravenous Artesunate were reported and our results showed its safe and excellent effect for a Japanese malaria patient.