A number of experimental research works on the strength and ductility capacity of structures have been carried out in the past, which showed that the ductility capacity was strongly affected by loading condition. As far as such a repeated loading as earthquake motion is concerned, the design based on ductility factor is not always reasonable. The authors have proposed that the energy absorption capacity of structures is wellsuited index for seismic safety. The purpose of this study is to investigate the energy absorption capacity of structures quantitatively. A series of five reinforced concrete columns were tested under four types of repeated loading. The results developed in this paper is intended to use in estimation of seismic safety.