PURPOSE: To achieve automatic weighing of bulk material to be held within a set range and in the shortest time, by computing a large supply time based on a multiple factors including a constant amount set weight and medium supply time at each supply to adjust the time of large supply.

CONSTITUTION: An air cylinder 4a for large supply and vibration supply machine 7 for small supply operate. Then, after a set large supply time T0 elapses, a medium supply air cylinder 4b starts after the large supply is stopped. Thereafter, the supply of rice to a weighing hopper 1 is weighed with a weighing device 3. When a specified amount is reached, the medium supply is stopped and the small supply only is executed. Later, the supply is weighed with the weighing device 3. If a specified amount is reached, the small supply will be stopped. The weighing device 3 is used to judge whether the supply is within a set weighing range or not. When it is the rice in the weighing hopper 1 is delivered and if it is not the large supply set time T0 is corrected.