Generally, when calculating the transverse strength of a ship, it is required to estimate not only the hydrodynamic lateral pressure but also the inside cargo load induced by ship motions. However, the effect of the inside cargo load on the strength has never studied in detail. Authors study on the wave load and the wave stress of bottom structure of a bulk carrier under the influence of inside bulk cargo. By our study, it is clarified that the extreme value of the wave load is evaluated to decrease in comparison with that of the empty hold, when the specific gravity of the cargo is less than about 1.0. In the case when the specific gravity of the cargo exceeds about 1.0, the value increases with the specific gravity of the cargo. So it is concluded that when the specific gravity of the cargo exceeds about 1.5, the ore cargo hold is in severer load condition than the empty hold considering the difference of still water loads between them. This result is very useful in designing bottom structure of bulk carriers.