A novel time‐dependent phenomenon has been found in the rheology of the disperse system of spherical particles. This is the phenomenon that the dynamic torque, i.e. the dynamic moduli, decrease with increasing dynamic shearing time to values lower than one‐thousandth of their initial ones and recover within a short time by the appropriate steady shear. This unsteady phenomenon can be repeated many times by repeating the shearing process. It is considered that the rigidity and the uniformity in shape and size of dispersing particles are important factors for this time‐dependent phenomenon.