The aim of this research is to determine the process of proving the existence of state finances losses as the basis for determining the criminal act of corruption in Decision Number 07/Pid.Sus-TPK/2017/PN.Mdn. this research is normative in nature, the data required is secondary data in the form of available data contained in legal materials consisting of primary legal materials, namely binding legal materials. The data collection technique is done by document study. The data obtained were then processed and analyzed by prescriptive and descriptive analysis. The results showed that proving the existence of state losses as the basis for determining the criminal act of corruption in Decision Number 07/Pid.Sus-TPK/2017PN. Mdn is based on the assessment that the defendant is a Commitment Making Officer in Machinery Procurement Activities/Laundry equipment at the Health Office, deliberately did not supervise, in the implementation of the contract it actually realized the payment of work without prior verification of the work results, which according to the Audit Result Report of the State Audit Agency of the Republic of Indonesia (BPK RI) had incurred expenses resulting in a State loss of Rp. 231,072,354.50 (two hundred thirty-one million seventy-two thousand three hundred and fifty-four rupiah and fifty cents). Keywords:Proof, state financial, loses, basis of determining criminal act of corruption