A card adapter mounted on a card connector in a state where a card is held is provided. The card adapter includes an adapter body guided by a guide member which guides a separate card different from the card when being mounted to the card connector, and mounted on the card connector so as not to come into contact with contact terminals for the separate card; and a holding portion making the card held by the adapter body in a state where a rear end of the card is made to protrude from a rear end of the adapter body. The holding portion includes an ejection mechanism ejected by once pressing the card held by the adapter body toward the deep side.