An experimental study was performed to obtain the data about the buckling strength of the columns using structural steel(SN490B) at high temperature. Two kinds of experiments under the centrally compressive load with rectangular cross-sections of thickness 10mm X width 26mm, (1)tests at constant high temperature, and (2), tests at increasingly higher temperature under a constant axial load. By ... [Show full abstract] the tests(1), the buckling loads of column models which were enforced axial edge compression at a constant-high temperature were examined. And, by the tests(2), the collapse temperatures of the column models at increasingly higher temperature under a constant load were examined. The results of these tests were compared on a chart of buckling curves, and the effect of creep strain on the buckling strength of the column models was investigated. Furthermore, numerical simulations of the tests were performed. And the results of the calculations clearly show that numerical analysis can be used to provide accurate predictions of the buckling characteristics of columns at high temperatures, when an appropriate mechanical model and data of steel materials at high temperature are used. Comparing the results of tests and analyses, the effects of creep strain (time effect) on the buckling characteristics of steel columns at high temperature are shown.