Generally, when designing the ore carrier, the Coulomb's theory of soil mechanics is used to determine the ore pressure which acts on the tank walls. However, the are pressure calculated using the Coulomb's theory is the static are pressure, and, actually, such factors as wave loads, ship motions, hull vibrations, etc., would demand due consideration. The authors, therefore, carried out some model tests to analyze the dynamic ore pressure and thereby formulated an experimental equation in order to estimate the ore pressure in more realistic manner. And, using the experimental equation thus formulated, the authors analyzed the distribution of ore pressure in the cargo tank of a 250, 000 tons deadweight ore carrier. Consequently it was found that the ore pressure acting on the longitudinal bulkhead in way of the wing-tank strut where a considerable amount of dynamic loads were exerted by wave, etc., would be 35 times greater than it was calculated using the Coulomb's theory, as a result of the static ore pressure being superposed by dynamic ore pressure due to horizontal and vertical ship motions and by pressure from the spring action of ore due to deformation of the longitudinal bulkhead.