A resonator includes a dielectric substrate, a conductor disposed over the dielectric substrate, and a high-dielectric pattern disposed between outer parts of the conductor. The conductor includes an arc part, which has a C shape, and the outer parts, which respectively extend outward from both ends of the arc part, such that the conductor has an omega shape as a whole. The high-dielectric pattern has a relative permittivity greater than a relative permittivity of the dielectric substrate. The resonator has a flat plate shape to increase a filling factor of a sample, thereby improving measurement sensitivity. Also, the resonator is miniaturized, and thus a biosensor system including the resonator is also miniaturized.