Multinational company engaged in mineral mining sector such as Freeport-McMoran, Rio Tinto, Newmont Goldcorp, and a few others has been conducting mining activity in Indonesia since late 1960s, using the contract of work model that is regulated in The Law Number 11 Year 1967 regarding The Principal Provision of Mining. The Law Number 4 Year 2009 regarding Mineral and Coal Mining set a new model of cooperation between the Government of Indonesia and foreign investors in mineral mining sector known as IUPK. The obligation to adjust the contract of work into IUPK is regulated in this new mining law. This cause absence of legal certainty. The contract of work that is still not yet expire oblige to adjust its provisions into IUPK caused overlapping in legal substances. On one hand the contract of work as an agreement ruled that the contract shall be respected until the end of the terms agreed by both parties. Whilst on the other the law oblige to adjust the contract of work into IUPK. Through this thesis, by using literature research methods and legislation approach, the author conduct an in depth analysis to find the solution most suitable for both parties. The result shows that negotiation and respecting the contract of work with regard to the law is a key solution. Because after all, both the government and foreign investor are bounded by the contract that the parties conduct and the law itself.