Japanese spotted fever (JSF), first reported in 1984, is a rickettsial disease characterized by high fever, rash, and eschar formation. A 61-year-old man was admitted to a local hospital in Nagasaki City, Japan, after several days of high fever and generalized skin erythema. His condition deteriorated and laboratory findings indicated disseminated intravascular coagulation (DIC). The patient was transferred to our hospital with mental disturbance and status epilepticus. Treatment included minocycline, and new quinolone. Definitive diagnosis was made with a serological test showing increased antibody levels against Rickettsia japonica. Rickettsial infections are rare, but should be seriously considered for the differential diagnosis of aseptic meningitis and encephalitis, as they show no response to conventional antibiotic treatment.