Card storage device for storing and transporting multiple media cards, the cards being of the same type or of different types. The card storage device has an adaptable media-card holder that allows the user to configure the storage device for specific types of media cards. The media-card holder includes an outer frame and middle and inner auxiliary frames that are optionally inserted into the outer frame. The outer frame provides a storage space for a large type of media card. The auxiliary frames provide secure storage space for one or more smaller media cards.