The electronic collection system(ETCS), is globally used in about 40 countries. In Korea, the Korea Expressway Corporation led the nationwide introduction of the ETC system in 2007 under the brand name of the Hi-pass. Since then, Hi-pass, with its rate of average daily use reaching about 70%, has become an essential facility in Korean expressways. To identify users` perception on Hi-pass (satisfaction, preference, etc.), this study conducted a Modified Importance-Performance Analysis (M-IPA). With this, this study attempted to identify the kind of efforts necessary to enhance current Hi-pass users` convenience and satisfaction. According to the result of M-IPA, the items including non-stop payment and toll are identified as key items that require further improvement. For improvement in the non-stop payment item, operations of Hi-pass booths appropriate for the demand for Hi-pass use and the selection of Hi-pass booths` locations in consideration of entry and exit lanes need to be improved. In addition, with regard to the toll item, although discount is currently provided to Hi-pass users, thus, PR thereof will have to be strengthened. It is expected that this study will be used as basic data to devise methods of enhancing Hi-pass usage through improvement of Hi-pass users` satisfaction.