To investigate the seismic behavior of pile foundation in layered ground of dense and cemented sand, a series of centrifugal and numerical modeling were performed. The centrifugal modeling tests were performed with a laminar box whose upper half was the dense sand, and the lower half was the artificially cemented sand. The model piles penetrated through both layers and were fixed at the bottom of the container. When subjected to a seismic motion, the upper layer of the dense sand reached liquefaction and did not resist to the lateral displacement of the piles. In contrast,

the bottom layer of the cemented sand maintained the lateral resistance although the excess pore pressure ratio reached nearly 1.0. Furthermore, effective stress-based, numerical analyses were performed by using the code FLIP to examine its applicability for such condition. The behavior of dense sand was well reproduced by the conventional model for liquefiable material. Meanwhile, the cemented sand was well predicted when modeled without the effect of liquefaction. These results highlighted the distinct behavior of the cemented sand whose shear stiffness did not immediately diminish during an earthquake.