Various excitation techniques for cantilever resonators immersed in liquids have been developed to achieve sufficient quality factors for reliable detection. In this study, we present a novel electrostatically-excited nano-thickness cantilever resonator with a transparent indium tin oxide (ITO) counter-electrode. The ITO was used along with the cantilever resonator which is heavily boron-doped for electrostatic excitation, allowing optical measurements of resonant frequencies as well. Quality factors of the cantilevers were significantly enhanced both in air and deionized water. We also observed linear relationships between the square of the peak-to-peak feedback voltage and cantilever dynamic deflection. We will further develop these resonators towards real-time measurements of biological particles in liquids.