The system fire research in Japan was started after World War II. One of the main objectives was the diagnosis of the strength remaining in buildings burnt out during the as against a future earthquake. The fire behavior in compartments and the structural behavior of building in the fully developed stage were studied by carrying out full scale fire tests in compartments during the 1950s. Later the objectives became the study of the flashover in a room and the smoke movement inside a building. Actual buildings scheduled for demolition were used for investigation of many items during the 1960s and 1970s. In the first half of this period the main purpose was the observation of real fire behavior. In the later half, a comparison between the test and the simulated results became the main objectives. It can be said that research on building fire in Japan has advanced through such full scale fire tests.