Dynamic centrifuge model tests were carried out to investigate lateral soil pressures acting on a pile in a liquefiable sand layer. The centrifuge model test consisted of a saturated sand model with embedded piles. Three model tests which were different in relative density of the sand layer were conducted. From the test results, we discussed the change in cyclic mobility occurring in the sand layer and the influence of cyclic mobility on the soil reaction along the pile. It was found that the continuation of cyclic mobility depends on the density of the sand layer. The effective stress recovery induced by cyclic mobility determines the soil reaction along the pile in the liquefied layer.