PURPOSE: To enable a supply system to correspond to full automatic operation in assembly work with no necessity for providing parts as a kit, by demanding the parts to be supplemented when a discriminating unit discriminates that a holding quantity of the parts subtracted in an arithmetic unit reaches a lower limit value.

CONSTITUTION: A plurality of detecting units 4, being provided in each station, detect an end of one unit assembly work in the station. While a station stock data file 5 stores in memory a parts list, original unit and a parts holding quantity in every station of parts used in assembly. An arithmetic unit 6 calculates a holding quantity for every part in a corresponding station by the original unit on the basis of detection by the detecting unit 4. Further, a discriminating unit 7, setting a lower limit value for the holding quantity of every part in each station, discriminates whether or not the holding quantity subtracted in the arithmetic unit 6 reaches this lower limit value.