PURPOSE: To attain ease of control of a dielectric constant and to obtain an excellent lens characteristic by providing a lens composed of resin composition made by dispersing low dielectric constant minute hollow spheres in a fibrous tetrafluoroethylene resin.

CONSTITUTION: The radio wave lens is made of a resin component dispersing low dielectric constant minute hollow spheres 2 in a fibrous tetrafluoroethylene resin 1. That is, the component comprising the fibrous tetrafluoroethylene resin and the low dielectric constant minute hollow spheres has independent porosity porous structure. Thus, even when the porosity of the radio wave lens made of the resin component is increased, no crash nor deformation takes place by an external force such as compression or the like. Thus, the stable lens characteristic with high performance is obtained and the porosity of the resin component is simply and surely adjusted by the selection of particle diameter of the minute hollow spheres mixed in the component and the blending rate and the lens as designed is made easily.