The problems of sloshing pressure loads have been investigated by many researchers. Recently, with the appearance of double hull tankers, the problem of sloshing pressure loads on double hull structures has become a matter of consideration. In these circumstances, the authors carried out sloshing experiments on four types of liquid tank structures including double hull structure. Main results of the experiments are as follows : (1) The sloshing pressure load on double hull structure do not become considerably higher than those on single hull structure (2) The swash bulkhead located in the middle of the liquid tank always works to prevent generation of high sloshing pressure loads. (3) The transverse rings fitted on the side wall of the wing tank work to make sloshing pressure loads lower than those on single hull structure. Then, the authors carried out a response analysis of double hull structure to sloshing pressure loads by the 1 DOF (degree of freedom) mass-spring system. As a result, the authors could obtain some suggestive knowledge of the structural response to the sloshing loads. This paper presents the results of the above experiments, along with the results of the structural response analysis.