Seepage erosion occurs when finer particles are dragged out from other soil particles by water. This type of erosion causes progressive failure inward into the slopes and slope instabilities. Therefore, it is necessary to explore the behavior of seepage erosion in order to prevent such failure in slopes. According to results of field investigations, we do seepage erosion experiments in a laboratory to understand the erosion behavior. After that, we utilize FEM soft-ware-FLAC5.0 in order to determine the feasibility of numerical analysis in simulating seepage erosion behavior.