Presently, there are some means of voyage estimations such as Hire base, Charter base, and Anticpated income and expenditure statement of voyage. The former two are the means of estimation for profit of a ship's voyage per a deadweight tonnage adn a month, and it is well used in the case of chartered ships. But it is somewhat meaningless for the shpowner who runs his ships for himself. The latter means for estimation is mainly used in western shipping, and do not set forth simpler way of comparing profit with another voyage or with another ship's employing in other route. And this paper has yielded an index of ship's voyage profit evaluation by building a model of ship's voyage evaluation formula, and the index may be used in evaluation of the new investigation of shipping as well as setting out a shiop in a voyage. The model has yielded a break even curve which may be used for deciding the amount of demurrage and the period of ship's port time for a specific voyage contraction.