Triaxial compressive re-loading testing was conducted under laboratory confining pressures to examine the Kaiser effect on rocks in the different stress state from that of rocks in situ. Two rapidly increasing points of cumulative AE count were to be observed. The two stresses of 1st and 2nd kaiser effect points were then compared with pre-axial stress and pre-differential stress. The estimated axial stress and the estimated differential stress are not influenced by confining pressure. Micro-crack model which generates AE at the secondary crack growth, is a good explanation of the experimental results. This model testing is found to be able to explain the Kaiser effect even under a different confining condition from that of pre-loading.