Low temperature experiments have been made to demonstrate the operation of LiNbO3 optical modulator with superconducting electrodes. The operation of the modulator for applied dc signals as well as microwave signals in the frequency range between 8 GHz and 12 GHz has been observed at temparatures as low as 4.2 K. The present results indicate a possibility of realizing high performance LiNbO3 optical modulators employing superconducting electrodes.