In Korea, industrial sector take up highest of value 56.0%, transportation sector 22.8% and residential sector 11.9% of a total energy consumption. Due to abnormal temperatures the residential sector is showing a high growth rate of energy consumption increased demand for air conditioning in 2010. As a result, we have suffered from a power shortage, energy saving of the residential sector has been highlighted until now. Index decomposition analysis is a methodology that decomposes the change of energy consumption level into activity effect, structure effect, and intensity effect. It could be applied to energy demand and gas emission. This method has been used to conduct energy consumption analysis on manufacturing and industrial sectors to establish and evaluate the energy policies. This study decomposed the change of energy consumption level in Korean Residential sector from 1990 to 2010 applying Index decomposition methods: LMDI. Analysis showed energy consumption of residential sector increased by annual average 2.2% for 20years and the biggest increase in energy consumption was due to the number of households. In the late 2000s, structure effect of residential showed up by annual average 1.6% as residential structure changed into excessive consuming type of energy sources, and also energy intensity has been improved from 14% to -2.2 %.