Issues of chronology on archaeological remains or relics have been a storm- center of controversy when various archaeological researches have been done. Sometimes there is a limit for figuring out issues of chronology by archaeological research. In that case, the field of natural science is often needed to work out issues of chronology. Among various subjects in natural science, archaeomagnetism plays an important role in dating archaeological remains for baked earth bearing relics. In particular, archaeomagnetism is of use for sites where directly excavated dating proxy is unavailable. Terrestrial magnetism changes along with the passage of time and leaves trace by many kinds of residual magnetization which could be called fossil of terrestrial magnetism. Archaeomagnetic dating method is used to assign a date to the archaeological remains in which baked earth is found by measuring the changes of terrestrial magnetism through the thermal remanent magnetization retained in baked earth. This study aims to constrain the age of fire at Buinsa, Daege, Korea using 27 samples that were collected from a layer of baked earth. Buinsa is famous for the place where kept the first edition of Tripitaka Koreana, which was lost in fire at the second invasion of mongolia. In addition, there is a record that there was revolt around this region in A.D.1203. According to archaeomagnetic dating, ages of A.D.1150~1200 and A.D.1130~1210 were assigned for the two building sites in Buinsa, respectively. To this end, it can be concluded that the layer of baked earth on the two building sites in Buinsa recorded the vestige of fire caused by revolt.