PURPOSE: To prevent the overweight of the commodities which are put in a simple bag by detecting a fact that the weight of the simple bag exceeds a reference level and producing a warning based on the detection output.

CONSTITUTION: When an automatic bugging device 41 starts its operation to a simple bag in the midst of the registration processing, a load cell 54 of a support stage always measures the weight of the simple bag that includes various commodities. This weighing operation is carried on until the bagging job is complete so that the weight of the simple bag never exceeds a prescribed reference level stored in a RAM 73, etc. If a CPU 71 detects a fact that the weight of the simple bag exceeds the reference level, the warnings are produced by the buzzers 79, 84 and 89 of the device 41, a bar code scanner 44, and an electronic cash register 45 respectively and then displayed by the displays 59 and 64 under the control of the CPU 71, etc. Thus it is possible to prevent the malfunctions of a bag holding mechanism and a bag transport mechanism and also to prevent the breakage of the simple bag.