Abstract To support a method for measuring tectonic stress using the Kaiser effect in acoustic emission (AE) in rock, two fundamental studies were carried out. In the first, the effects on the Kaiser effect of both stress level and elapsed time after unloading were investigated for a granite in uniaxial compression. The Kaiser effect was observed clearly below the onset of dilatancy. However, AE activity in a pre-stressed specimen tended to recover with elapsed time. In the second study, model tests were carried out to investigate the mechanism of the Kaiser effect at low stresses by using a glass plate containing an inclined crack. Both the Kaiser effect and the recovery of AE activity with elapsed time were observed in association with sliding of the closed crack surfaces. Recovery of AE activity with time coincided with time-dependent recovery of residual shear displacement along the crack.