PURPOSE: To supply grain at a proper time, by equipping a grain storing device having an air conditioning means with a means to detect the residual amount of grain in a storage tank, a means to display the detected value at the exterior of a house and a means to feed grain from the exterior of the house to the tank.

CONSTITUTION: A storage tank 1 is equipped with a feed opening to feed grain from the exterior of a house to the tank and with an outlet to discharge the grain to the interior of a house, a means 15 to detect the residual amount of grain is set in the storage tank 1 and the detected value is shown on a means 29 to display residual amount power. An air conditioning means to control temperature and humidity in the storage tank 1 to given values is set and a grain storage device is composed of the tank and the above-mentioned means. When a grain salesman supplies grains at a proper time by the display of the residual amount at the exterior of the house, complexity of grain consumers in the house to confirm the residual amount of grain and order of grain is eliminated.