Liquefaction during earthquakes induces such damage of existing structures as uplift or settlement, depending on the weight of structure. It is important to mitigating damage occurring by liquefaction to take some countermeasures against harmful vertical displacement. This study specifically focuses on countermeasures against settlement induced by liquefaction of existing structures with sheet pile walls during earthquakes. For this purpose, the study considers the effects of sheet pile walls on decreasing liquefaction-induced settlement of existing structures using the model tests under normal gravity (1 g) conditions that simulate the situation of existing structures founded on sand deposits. Results show in the following: (1) The longer the sheet pile walls that are installed, the more markedly settlement of structures can be reduced. (2) Combined adaptation of sheet pile walls installation with a decrease in groundwater level engenders a great degree of reduction in the settlement of structures than with adaptation of the single technique of the sheet pile wall installation or dewatering of GWL.