The frequency of the ages of the HIV/AIDS deaths and that of the patients detected before or after the development of AIDS followed normal distribution. The median of HIV/AIDS deaths was 40-44 years in 1995-1998 and 50-54 years in 2014-2016, while the median of detection of the infection as “HIV” or as “AIDS” was constantly 25-29 years; it implied that the survival time of the HIV/AIDS patients became longer by 10 years in the past twenty odd years. The lengthening of the survival time could have been attributable to introduction of HIV/AIDS therapy, such as HAART. Importantly, however, during the same period, the life span of Japanese population was lengthened by near 10 years. Under the assumption that HIV/AIDS patients died 20 years after detection of the infection, the total number of the deaths was 1,446 in 1990-2016, which was close to the total number in Vital Statistics during the same period 1,532.