Experimental study on steel exposed column bases with a steel foundation has been carried out, and restoring force characteristics of the column bases are shown to be slip-type models. The column bases are usually constructed on concrete foundation so that the failure of concrete must affect the restoring force characteristics of the column bases. Therefore, two types of concrete foundations are employed to examine the effect of the failure on the characteristics of the column bases under monotonic or cyclic horizontal loading. The experiments are carried out and the following conclusions are drawn. 1) The models of cyclic characteristics are in good agreement with the experimental results of column bases with the steel foundation and with 50mm mortar on the concrete foundation. 2) In case of 150mm unreinforced concrete on the concrete foundation, the experimental result shows to be lower than the model because of the failure of concrete. 3) The failure of concrete at RC column to steel roof beam connection caused by 2001 Geiyo Earthquake can be considered to be similar with the failure of concrete foundation destroyed by the base plate of column base.