A game media processor of the present invention includes: a card insertion slot, into which a card is inserted; a shutter mechanism driven to make the card insertion slot closable; a card housing portion which allows the card to be housed therein; a carriage path, along which the card moves from the card insertion slot to the card housing portion; a card carriage mechanism which carries the card; and a control means for controlling the operations of the card carriage mechanism, the shutter mechanism including an oscillating member oscillatably supported by a shaft, the oscillating member having a closing portion formed on one end side configured to make the card insertion slot closable and a projecting/withdrawing portion formed on the other end configured to be able to project and withdraw from the carriage path, the closing portion being configured to close the card insertion slot by oscillation of the oscillation member caused upon engagement of the card with the projecting/withdrawing portion, wherein the controlling means controls the operations of the card carriage mechanism, on condition that a predetermined signal is received, so as to carry the card housed in the card housing portion to a position where the card is in engagement with the projecting/withdrawing portion.