To eliminate the chance for making fraudulence doers ran away by creating a situation which makes staffs notice possible fraudulence but keeping the fraudulence doers unaware of the exposure of the fraudulence.

An alarming control part 200d selects the case where no actual error occurs out of a plurality of error cases (errors of token clogging medal selector, hopper tank emptiness, overflowing of a hopper tank and clogging with tokens put out of hopper) pertaining to game machines to give an alarm of the error when a fraudulence is detected. The conflicted alarming of the error makes only the staffs notice the fraudulence.