Nowadays, investment holds an important role in Indonesia since the investors are facilitated by the Indonesian government to invest in various sectors. On top of everything, Indonesia has a lot of natural and human resources that encourages the Indonesian government to promote investment in front of foreign and domestic investors to boost economic matters. Over and above, Indonesian government through finance minister regulation empowers the investors by offering import duty facilities for machinery and raw material production (master list) to attract the investors to invest in Indonesia. For the sake of attracting investors, Indonesia Investment Coordinating Board (Badan Koordinasi Penanaman Modal – BKPM in Bahasa Indonesia) as the official agency for investment in the territory of the Republic of Indonesia is responsible for administering the investors by remarkable services. One of the services provided by BKPM is Master List Online System to process approval of master list. This innovation has been implemented and used by employees of BKPM and investors since June 2015. Offering 24 hours and 7 days of access, the system is expected to help the users. Along with this line, this study scrutinizes users’ acceptance and behaviour in the use of this system according to Task-Technology Fit (TTF), trust, usability, and Unified Theory of Acceptance and Use of Technology (UTAUT) by spreading questionnaires to the employees of BKPM and investors. Not to mention, the results of this research attest to what degree the effort expectancy and trust in public e-service affect the behavioural intention, then behavioural intention and usability of the system influenced the users' acceptance and the use behaviour. Once and for all, this study can be used as the evaluation and inputs for BKPM.