The present invention provides a consumable goods management tag,
comprising: a rewritable memory for storing remaining quantity data
representing a remaining quantity of consumable goods, and a rewrite
controlling unit for controlling a rewrite of the remaining quantity data
stored in the memory on the basis of a remaining quantity data writing
request inputted from outside, carrying out the rewrite of the remaining
quantity data responding to increase of the remaining quantity only when
a predetermined rewrite condition is fulfilled, and carrying out the
rewrite of the remaining quantity data responding to decrease of the
remaining quantity even when the rewrite condition is not fulfilled.