Abstract.—The mechanism of Kaiser effect was studied with the aid of a damage model for rock. Recognizing that the AE counts are transient elastic waves due to local damage of the rock, the quantitative relation between AE counts and statistical distribution of the local strength of the rock has been established. Subsequently, according to Damage Theory, an expression for Kaiser Effect under uniaxial stress state was derived from the model. This is found to be in good agreement with the experimental results.