To test of the efficiency of the automatic irrigation system controlled by soil moisture sensor, potatoes were grown in the plastic film house with six irrigation rates. Soil moisture sensors were installed in the center of the plot at 10, 20 and 30cm depth and set soil moisture content by the summations at each depth. Irrigation timings were controlled by automatic water pumps. Amount of applied waters at each treatment was monitored on daily basis. Result showed that a relatively constant soil moisture contents in 0�`30cm depth was maintained in each plot. Weight of potato were significantly increased by increasing amount of water application, but the numbers of tubers were not different among the treatments.