The acoustic emission response from porous rocks subjected to the freezing was explained. Using Tuff from Ohya as test specimens, samples were subjected to the freezing-thawing cycles with water supply. When the pore water of rocks started to freeze, a minor acoustic emission was detected. However a major acoustic emission response was monitored during freezing of pore water and process of water migration of water through rocks. The breakdown of rocks and a major acoustic emission responses were coincided with together. These responses indicate that the microcracks in rock formed at first, then large crack occurred.