Filling holes with liquid, or discharging gas from holes, is a fundamental process in both cleaning and painting. Discharging gas from small holes with closed end and high aspect ratio is extremely difficult due to surface tension. In this study, we developed a new gas discharge process from a hole by using acoustic wave irradiation. We irradiated two types of acoustic waves: waves with constant frequencies and those with variable frequencies in time i.e. sweep wave for test samples in a water pool. In addition, we observed gas discharge using high-speed video camera. As a result, we succeeded in completely discharging gas by using sweep frequency of the acoustic waves. From the observation results, we confirmed that gas discharge consists of three stages. The gas was discharged from the hole mainly at the first and third stage. In these stages, the natural frequency of the gas column in the hole was essential. In the second stage, the gas column in the hole breaks into multiple gas columns; then, the gas was hardly discharged even with the acoustic wave irradiation.