A portable wireless device has no portion which protrudes to the outside even in the case where a card type function medium is inserted. The portable wireless device has a small size and a high antenna property. The portable wireless device comprises a card slot (12) on a substrate (11) of a lower housing (10) and a slot cover (13) which can close the opening portion of the card slot (12). A non power supply element (14) is integrally formed with the slot cover (13). The non power supply element (14) is arranged in such a manner that the non power supply element is close to and approximately in parallel with an antenna element (102) of an SDIO card (100) when the SDIO card (100) is attached. The non power supply element (14) has an electrical length which is approximately the half of the wavelength of the driving frequency of an RF circuit (101) of the SDIO card (100). The non power supply element (14) is electromagnetically connected with the antenna element (102) and operates as a non power supply element.
