Improvement of energy efficiency has been a major public policy concern in Korea. Investment cost for location of avoidance facility such as nuclear power and radioactive waste management facility, environmental pollution etc could significantly reduced from improvement of energy efficiency. Energy efficiency improvement could be one of good solution to cope with volatile energy market. Korea has been high oversea dependency in fossil fuels supply to meet its energy requirement. Its import dependency on fossil fuels in 1995 and 2000 is respectively 96.8% and 97.2%. The fact that Korea depends heavily on imported energy shows it should make more efforts to promote improvement of energy efficiency. Although Korean Government has supported industrial sector in improvement of energy efficiency, some energy analysts and critics point out that Korea has little progressed in energy efficiency improvement. This paper estimated its energy efficiency and analyzed its improvement with energy Input-Output table 90-95-2000 of Korea. The results are appeared differently. The cross section and time series analysis result of the energy efficiency is that energy elasticity for GDP, energy intensity and induced energy consumption between 1995 and 2000 significantly improved. From 1990 to 1995, energy elasticity for GDP is bigger than 1. It means that energy consumption increased rapidly more than GDP growth rate. This is the evidence that energy efficiency was not improved. Energy intensity of each industrial sector between 1995 and 2000 is lower than in cases of1990 and 1995. It shows that energy efficiency was improved. As energy intensity of each industry becomes lower, induced energy consumption of economy goes smaller because of interaction among sectors.