A card apparatus includes a card case housing a circuit substrate, a case main body and an extended portion made of resin material and being disposed integrally with the case main body. The extended portion accommodates one end side portion of the circuit substrate. The case main body includes a metal cover disposed opposite to at least one of the front surface and the back surface of the circuit substrate. A metal cover extension extending from the metal cover and constituted of a first conductive plate is embedded in a case wall constituting the extended portion, and a second conductive plate constituting an antenna element is embedded in the case wall constituting the extended portion, the second conductive plate being provided at a predetermined distance apart from the metal cover extension.