In order to understand the capability of monitoring ground water movement by ground penetrating radar (GPR), we carried out a field survey in Mongolia. We controlled water production at a ground water source area and the change of ground water level at about 5 m in depth could be detected by GPR. The change of the ground water level was observed more than 15 m in the radial distance from the pumping well. The change of the vertical water content was also evaluated by GPR.