The present invention provides an improved card adapter structure which includes an upper cover, a lower cover and a converter terminal set. The upper cover is designed to conform to short memory card specifications, wherein an insertion slot is defined at the rear of the upper cover corresponding to the shape of a micro memory card. A port is configured in a central portion of the lower cover to accommodate a micro memory card. The converter terminal set is configured with eleven terminals, wherein an injection molded fixing mount fixedly covers each pin of the converter terminal set, and eleven pins extend outward towards a short memory card opening. Pin three and pin six are jointly configured with a large grounding area, and eight pins extend outward towards the micro memory card port. Accordingly, the adapter structure conveniently converts a micro memory card into a short memory card.