The relations of magnetization differential with magnatic intensity describedby dM/dt-H curves are studied in Ni-Zn ferrite with a constant rate of increasing H.It is shown that dM /dt-H curves depend on the rate to increase H and dM/dt increaseswith increased H for a fixed temperature. For fixed H

dM/dt-H curres are lower forhigher temperature. Analytic expression for dM/dt is derived and the ratio of dampingcoefficient to restoring coefficient is measured to be in order of the l0￣(-5)～10￣(-6)s.