A unit of a metamaterial includes an uppermost part electrode, a lowermost part electrode, a first internal electrode, a second internal electrode, a third internal electrode, a fourth internal electrode, and a transmission line. The transmission line connects a section of the uppermost part electrode which extends in the −z direction to a section of the lowermost part electrode which extends in the +z direction. The length of the transmission line is set to substantially ½ of a resonant wavelength. The first internal electrode and the fourth internal electrode are respectively placed so as to be opposed to the uppermost part electrode and the lowermost part electrode. The first internal electrode and the fourth internal electrode are not electrically connected directly to each other.