This paper shows a micro-economic based quantitative analysis scheme to evaluate the energy efficiency of cities based on quality of life and energy consumption. By representing the quality of life by utility, this study developed a CES-based model to estimate the individual demand of non-mobility goods, car trips, and public transport trips at the maximum utility level. Energy consumption is estimated by the demand of goods. An energy efficiency index is developed to show the relative energy consumption on the certain quality of life. We applied this model to Nagasaki region. Higher energy efficiency zones were found in city center and along the mass transit lines. Such findings suggest that a compact urban structure and higher public transport accessibility could increase energy efficiency.