To facilitate the control of the directivity of a surface-mounted antenna which is incorporated in a radio device such as a portable telephone and to alleviate an influence in difference in its position on its transmitting and receiving performance.

An earth electrode 3 is formed on one principal plane 2a of a pentahedral substrate 2, and a radiating electrode 6 is provided on the other principal plane 2b in such a way that one of its end constitutes an open end. The other end of the radiating electrode 6 is connected to the earth electrode 3, and a feeding electrode 9 is formed on an edge 2c of the substrate 2. The radiating electrode 6 is non-parallel to the earth electrode 3. In this way, the radiating electrode 6 can be mounted on a substrate of a radio device such as a portable telephone in an inclined state with respect to the substrate and can receive radio waves not only from above but also from the side in a favorable condition. Costs of the surface-mounted antenna 1 can be reduced by reducing the volume of the substrate 2 while suppressing a deterioration in electrical characteristics by eliminating electrically less important parts of the substrate 2.