A metamaterial that includes a metallic wire and a supporting member. The metallic wire has a length of substantially half the wavelength of electromagnetic waves, and is coiled in the shape of a spring. The supporting member fixes the metallic wire such that the central axis of the metallic wire is parallel in direction to an electric field generated between a signal line through which an electric current flows and a ground. The metallic wire placed in such manner resonates with electromagnetic waves having a wavelength approximately twice as long as the metallic wire, and exhibits a negative dielectric constant.