Stresses are generated in soft clay ground if external loads such as an embankment are applied to its ground. It strongly affects the stability of structures such as foundation piles and underground pipes adjacent to the external load on the foundation ground. Since the lateral flow generates an external force on the structures in foundation ground, the lateral flow must be estimated accurat ely as a earth pressure. However, the lateral earth pressure induced by the lateral flow is affected by the magnitude and the construction speed of embankment, geometric conditions and characteristics of embankment and foundation ground, etc., and is caused by the interaction of shear distortion and volumetric deformation due to consolidation. Therefore, it is much difficult to establish an accurate method for estimating the lateral earth pressure. This paper presents the results of a series of centrifugal model tests that are carried out in order to clarify the effects of the strength distribution in foundation ground and to study the effects of the safety factor expressing the relative magnitude of the applied embankment load for the lateral earth pressure in the foundation ground, arise from the construction of an embankment.