Bank is a financial institution that plays an important role in the economic activity of a country. Bank in carrying out its functions, is inseparable from the role of the customer as a consumer. The relationship between the bank and the customer, where the customer is acting as businesses and consumers can not be separated from the conflict. The problem is when there is a conflict, we need legislation that governs the protection of customers. Then the author tries to track down any regulations governing the protection of bank customers, associated with the decision No.03/ Pdt.BPSK/2011/PN.MKS Jo 769 K/Pdt.Sus/2011 decision. In conducting this study the authors used normative legal research methods, research was conducted to collect and analyze secondary data, solving problems or legal issues present in society. The results show that the bank was providing protection to customers in the form of information on the risk of the use of bank products. Then protection to customers is reflected in the form of responsibility to the bank of it’s products are used by customers in the form of indemnity. If an error occurs due to negligence of the bank. In the case of the Bank Mandiri and it’s customers, the Supreme Court ruled that independent banks should not be responsible for errors occur due to negligence of the customer and not the negligence of the bank