There has been strong international interest in students' understanding concerning phenomenon taught in physics. Many studies have been conducted to find out students' conceptions in various concepts in physics. This study was designed to find out students' conceptions of the relationship of energy use and technological development in energy. It was conducted by administering a questionnaire to 133 first year physics students at a university. A questionnaire entitled "Questionnaire On Energy And Technological Development" was used to collect data for this study. The results were analyzed to identify students' conceptions on energy use and technological development in energy. Finally, implications on teaching of energy is discussed in this paper.