Blueberries are popular early summer fruits. While high temperature in the harvest period induces ripeness of fruits, increases tidal volume and cause reducing their hardness. This result in weight reduction and deterioration of fruits. So, controling temperature of harvested fruits is important to keep storage quality and shipping quality. To decrease the temperature of harvested fruits, we made a precooler using differential pressure method. With infrared thermometer we measured the temperature change of harvested fruits and reviewed the application and utility of the precooler.