As household energy consumption has increased, serious environmental problems such as resource depletion and global warming have become global issues. Thus, consumers worldwide are trying to protect environment by looking for efficient ways of energy saving. It is essential to conduct the energy use of residents living in apartments, which account for over 50% of the Korean housing market, in order to come up with alternative solutions of energy saving. Therefore, this study examined the energy use awareness of apartment residents and their energy use behavior by types of awareness. For this purpose, survey was conducted of housewives living in apartments in Busan, and 349 cases were analyzed by the SPSS WIN 12.0 program. To understand their energy use behavior according to awareness of subjects, the energy awareness dimension was made up of five factors and they were subject to cluster analysis, and then the subjects were categorized into three groups. G1 is indifferent to energy savings and thinks that convenience is important factor. G2 is conscious of energy use costs at inconvenience. G3 is aware of energy saving, but indifferent to energy costs.