PURPOSE: To efficiently perform picking operations of a desired number of desired parts, by reading the unit weight of the desired parts and tare of the container marked on the container by means of a detecting means installed to a part of a scale.

CONSTITUTION: At one corner of the bottom section of a container 17, for example, weight of one piece of bolt and tare weight of the container 17 are marked with bar codes. When the container 17 is put on the scale 31 of a digital counter 30 by positioning with a bar 37, the mark on the container 17 is read by a bar code reading member on the scale 31 and the read signal is supplied to an arithmetic circuit and storage circuit in a casing 39. The weight, unit weight, and number of the content of the container 17 are displayed in display sections 32W34 based on the read signal.