Abstract: A shutter mechanism used for card module opens and closes a card module slot of electronic device installed on a motor vehicle. The shutter mechanism has a shutter body and a card holding section. The shutter body is reciprocally movable between a closing position closing a slot and an evacuation position apart from the slot in a direction perpendicular to a direction of inserting the card into the slot and in a direction of a surface of the card inserted into the slot. The card holding section is arranged on the shutter body to press a rear end of the card, which is inserted into the slot when the shutter body stops at the closing position, in the insertion direction of the card.