The effect of an electric field on the concentration of impurity in the solid phase for the 3,5-xylenol + naphthalene system was experimentally examined by applying a de electric field in parallel with the solid-liquid interface during solidification. Furthermore, the solidification rate and the flow pattern in the liquid phase were also observed by using a microscope. The concentration of the impurity (naphthalene) in solid 3,5-xylenol was decreased by an electric field. This may be due to the turbulence in the liquid phase induced by the electric field. The impurity near the solid-liquid interface can be removed by the turbulence.