The present study proposes the hypothetical validation of the relationship between key success factors and ERP implementation success. There are twenty KSFs considered in this study which were chosen from literature review. The success of ERP implementation can be measured through five indicators, namely: system quality (SQ), information quality (IQ), service quality (SEQ), tactical impact (TAI) and strategical impact (STI).There are 248 respondents who represent 37 companies and 10 industrial sectors that responded to the questionnaire. The respondents are staff at management level, IT staff and users involved in the development and use of the ERP system. Based on hypothetical validation, the ERP implementation can be success when all of independent variables (x1...x2D) have value of S (satisfied) or when any of (x1...x2D) have value of NS or S. If any of (x1...x2D) have value of NS, then the other factors that have a significant influenced to ERP system implementation success must have value of S in order to gain a successful of ERP system implementation. The ERP implementation is absolutely failed, when all of independent variables have value of NS (not satisfied). There are several limitations in this study, where the degree of ERP implementation for each company is not the same in terms of the number of module implemented, ERP system product used, and so forth. Further, the companies involved in this study have different numbers of years in using ERP system. This study is expected to improve knowledge in ERP implementation, especially the validation of the relationship between key success factors and ERP implementation success.