To provide an antenna which has little deterioration in a characteristic even though the antenna is made thin.

In the antenna provided with an antenna element 1 and a reflector 2, the antenna element 1 is made, for example, of copper foil, and is in the shape of a rectangle surrounded with a base side, a top side, a left side and a right side. A feed point 3 is set on the base side being a long side of a rectangle of the antenna element 1. The reflector 2 is arranged in the rear face of the antenna element 1. Since electromagnetic coupling between the antenna element 1 and the reflector 2 is relaxed by forming a notch 5 in the antenna element 1 of such an antenna, an antenna characteristic hardly deteriorates even if a distance between the antenna element 1 and the reflector 2 is made narrow.