Japanese encephalitis is a mosquito-borne flaviviral infection, which has a wide distribution in Asian countries, including Japan. The clinical illness may manifest as a febrile headache syndrome, aseptic meningitis, or encephalitis with a number of cases of subclinical infection. Japanese encephalitis is a vaccine-preventable disease. The mouse brain derived inactivated vaccine was first developed in Japan in 1950s. In 2009, this original form was replaced by the Vero cell derived product. The results of clinical trial and post marketing investigation on the Vero cell derived inactivated vaccine showed good immunogenicity and safety profile. High immunization coverage should be encouraged to prevent people from Japanese encephalitis.