PURPOSE: To eliminate the need for inputting data from keyboard into a microcomputer when operating an electronic weighing machine.

CONSTITUTION: Each bag is marked with its volume with bar codes. When a scanner 31 reads a bar code marked on a new bag 10, a CPU 30 extracts information corresponding to the bar code information from a memory 32 by collating the bar code information with information on a memory 32, and inputs the extracted information into a controller 19, which sets its internal weight memory so that the memory agrees with the above bar code information. Thus, the weight of a material to be filled in a bag 10 automatically agrees with the bar code information.