A playing card

摘要

In the present invention, an identification code (11) representing that a playing card (10) constitutes a prescribed group is given to the playing card in order to discover an abnormal playing card (10) mingled in with genuine playing cards for illicit purposes. The identification code (11) is read from each of a plurality of playing cards constituting the prescribed group so as to determine whether the playing card is a genuine playing card or an abnormal playing card. The identification code (11) may be provided on the playing card (10) in a condition invisible to the human eye under normal usage conditions.