Recently intensive studies have been focussed on ferrites which have high magnetic loss because of the increasing need for the prevention of EMI (Electromagnetic Interference). We investigated effects of microstructures of Ni-Zn ferrites on magnetic losses, magnetic properties, and behaviors of electromagnetic wave absorbers. The characteristics of the absorber were influenced by the sintering conditions. A Ni-Zn ferrite with the thickness of 7$^{circ}C$/min and the cooling rate of 7$^{circ}C$/min. It satisfied the absorbing properties in the wide frequency ranges including VHF (90∼220 MHz), UHF (470∼770 MHz)