PURPOSE: To prevent generation of loss by unfair use by storing proper key judging information of a disused key means and, when a key means is used, comparing its proper key judging information with the stored proper key judging information of the disused key means with an unfairness preventing processing signal output when both kinds of information are in agreement with each other.

CONSTITUTION: At the time in which any of the card 1000 is confirmed missing, a recital number, which is the second proper card judging information of the lost card 1000, is left as stored as a number of the lost card 1000 in a central control device 2000 and a unit control device 2210 of each PACHINKO (Japanese vertical pinball) machine 100, when the card 1000 is confirmed to be used by a proper information read means 600 of a card reader, a lamp and an alarm sound, which are unfairness preventing means, are immediately lighted and alarm generated. Simultaneously, the code number as the second proper card judging information of the lost card 1000 is removed from the set code numbers of the central control device 2000 and the unit control device 2210.