In this paper, we have studied the effect of earth (Gd, Er) on the various properties (microstructure, shrinkage, initial permeability, permeability as a function of frequency, etc) of Ba-ferrite. The permeabilities were analyzed by Impedance Analyzer(100KHz~40MHz) and Network Analyzer(30KHz~3㎓). As the result of XRD, all of the Ba-ferrite doped with rat earth was found to be Y-hexagonal phase. The resonance frequencies at the maximum imaginary value of complex permeability were observed near 2㎓. The complex permeabilities of the Ba-ferrite doped with Gd$_2$O$_3$at 3wt% and doped with Er$_2$O$_3$at 3wt% and 5wt% as a function of frequency showed the highest value at sintered temperature at 95$0^{circ}C$/3h.