The fines contained in covering soils of artificial tidal flat are sometimes washed out by waves and currents, inhibiting the creation of favorable ecosystem. The movement of the fines in soil under one-dimensional water pressure change was studied experimentally. The sandy soil containing 10% fines were subjected to the cyclic water pressure change, and in some conditions, it was observed that the fines moved to the upper directions in the soil and finally reached to the surface. The upward movement of fines took place when the water pressure decreased and the pore pressure in the soil became larger than the water pressure, and it is suggested that the occurrence of liquefaction under the cyclic water pressure change was closely related to the upward movement of fines in the soil.