This study aimed to explore customer satisfaction towards service quality of Chiang Mai Provincial Electricity Authority. Data were obtained from 400 electricity users taking services at Chiang Mai Provincial Electricity Authority and asking for off-site services. Questionnaires were used to collect data. In order to assess levels of customer satisfaction, the evaluations on expectation and perception towards 5 service aspects: tangibility, reliability, rapid responsiveness, assurance and attendance to individual were applied. All acquired data were analyzed by the descriptive statistic, consisting of frequency, percentage and mean, as well as the T-test. Hereafter were shown the finding summary. The findings presented that the overall satisfaction of users towards service quality of Chiang Mai Provincial Electricity Authority was ranked at high level. For the individual users using electricity for residential purpose, they satisfied with all aspects. For organizational or business users, they satisfied at the highest level to 2 aspects namely assurance and rapid responsiveness, at the high level to 3 aspects namely tangibility, reliability and attendance to individual. According to the difference test (T-test) between expectation and satisfaction on actual services, the results showed that the expectations of two groups of users were not different. However, in the overall view, the satisfaction on actual services among these two groups was different in all aspects. Here were four sub-factors that the difference was found: 1) the responsibility of officer to completely accomplish all tasks being informed to customer, 2) the availability of drinks for waiting customers, 3) the good assistance from officers when having petition or urgency and 4) the explicit understanding of officers to a specific need of each customer.