A sheet-type metamaterial of a film configuration to exhibit a figure of merit (FOM) exceeding 300 in a terahertz wave band. A film-shaped dielectric substrate has a front surface on which a first wire array is formed, and a back surface on which a second wire array is formed. The first wire array includes elongated metallic first cut wires of a predetermined length l aligned in a y-axis direction with a gap g therebetween and in an x-axis direction with space s therebetween. The second wire array includes second metallic cut wires having the same shape as the first cut wires and aligned to overlap the first cut wires. With a thickness d of the dielectric substrate set at about 50 μm, the length l of the first cut wire and the second cut wire is a length approximate to a value to generate resonance at a design frequency.