An Analysis of Management of Optimum Supply Cash Reserve at Pluit Kencana Outlet of "Y" Branch at "X" The aim of this research are analysing characteristic of customer transaction, evaluating applying of management system of cash reserve, and determining optimal supply cash reserve in Pluit Kencana outlet of "Y" Branch at "X" Bank Limited. To analyse the characteristic of customer transaction in Pluit Kencana Outlet conducted by interview with the head and teller in this outlet, and analysed based on data of transaction of endorsement and withdrawal customer during 1 year ( January - December 2005) seenly is daily trend. Determining optimal supply cash reserve in Pluit Kencana outlet is used Miller-Orr Model. The Average of the biggest incoming cash transaction in Pluit Kencana is the Monday per month, at second week and in each date of 25. For the outgoing cash, the average of the biggest transaction also on Monday, every date of 25 and fourth week per month. The average of the biggest remise happened on Monday, second week per month and every date of 2. While supply, the biggest average happened on tuesday, every date of 14 and first week per month. The smallest transaction mean for the cash of incoming and cash go out became on thursday, every date of 1 for the cash of incoming and date of 20 for the cash of go out and at third week per month good to incoming cash and cash go out. For the smallest remise mean happened on wednesday, date of 1 and week of third. While for the supply of on Monday and Friday, at date between 16 to 20, date of 22 and date of 23, and date of 29 and date of 31 and week of third. Optimum cash balance for Pluit Kencana Outlet by using model Miller - Orr is Rp. 424 Million with the boundary of under or minimize the Rp. 368.43 Million and boundary for or maximal of Rp. 535 Million.