Residential electricity consumption and relevant demographic factors in the urban and rural areas of Cambodia and Phnom Penh were estimated by the raw data of the Cambodia Socio-Economic Surveys (CSES) conducted in 2004 and 2009. It was found that the public power supply spreads rapidly and the median household electricity consumption increased 30% in each area between 2004 and 2009 while the median of nominal monthly household income increased 100% in the same period. Positive correlations between household size, income, and electricity consumption were also revealed by the Jonckheere-Terpstra test.