Disclosed is an annular resonator including a conductor formed on a surface of an annular shaped structure and having a first end and a second end opposite to the first end, and a capacitor having a first end and a second end opposite to the first end, wherein a radius of curvature of a first side facing a center portion of the annular shaped structure is smaller than a radius of curvature of a second side facing an outer periphery of the annular shaped structure, and wherein the first end and the second end of the conductor are electrically connected to the first end and the second end of the capacitor, respectively.