Because the global shortage of water is expected, saving water of the agriculture water is necessary. Therefore, the irrigation method using the minus pressure difference of soil water attracts attention for saving water. This method has the nature keeping the water content inside the ground. In other words, when there are crops, it is the mechanism which supplies the water content which is same quantity with the water content that it absorbed. However, effective saving water is not able to be performed, because the water distribution in soil is difficult to grasp. Therefore, we propose a method of monitoring and imaging of the water content in the rooting zone using a sound vibration. From the experimental result, we confirmed that the distribution of the propagation velocity of sound was a very effective method to the water distribution which is in the shallow position near the sand surface. Also, in the experiment which used negative pressure irrigation, we confirmed that an approximately real time measurement of the water distribution was possible from the distribution of the propagation velocity of sound. In addition, we confirmed that the propagation velocity of sound was proportional to the water content from the measurement result of the water sensor in the sand. As a future task, we intend to examine whether our method can apply even in the case that a plant is growing up in soil for gardening.