PURPOSE: To prevent a cumulative measurement of the whole from coming to naught, by measuring first a raw material for which it is not desired to generate the remaining quantity, and measuring the following raw material at the same rate as a rate by which it has become an end quantity, when it has become the end quantity.

CONSTITUTION: A kind of a recipe 7 and its production quantity are registered by a registering device (CRT) 5, and simultaneously, a set weight of a recipe 8 is calculated and set. By a start command from the CRT 5, an operation command is outputted successively to a feeder 2 in accordance with the contents of the recipe 8. When the feeder 2 is operated, a raw material in a mixing tank is cut out and thrown into the inside of a weighing instrument 3. The weighing instrument 3 transmits a weight value signals which has matched the thrown-in raw material, and an arithmetic and control unit 6 turns off the operation command of the feeder 2, when the signal of the weighing instrument 3 has coincided with a set weight of the recipe 8. In this case, as for chemicals, etc. which are brought to a preceding measurement, one weighing instrument of the weighing instrument 3 is designated fixedly to the recipe 7, and in accordance with it, the preceding measurement is executed. In case the measured value is below an allowable value and the unit 6 has detected the generation of the end quantity, a new recipe 9 is prepared and the measurement is continued by a corrected measuring weight.