A card processing unit may include a card processing part for performing predetermined processing to a card, a card stack part in which a plurality of cards are stacked and stored, and a card feeding part for carrying a card between the card processing part and the card stack part. The card stack part may be structured such that the card stack part is capable of being separated from the card feeding part as a module and mounted on a main body base as a module. A plurality of card stack parts and a plurality of card processing parts may be mounted on the main body base as modules.