Originally, the consecutive method was proposed by Wang [1] to determine inventory policy for the non shortage case. Later on Astanti and Luong [2] extended the work of Wang by developing new algorithm based on consecutive method for shortage case but limited on completely backlog situation. It is noted that the shortage case is the situation when customer arrive but the goods are not there. When all customers are willing to wait until the next replenishment, it is called completely backlog situation. However, in the real situation it often happens that some customers are willing to wait, but the other prefers to find another supply sources, or it is called partial backlog case. The work of this research, therefore, is going to develop the algorithm for determining inventory policy with partial backlog case.