The electromagnetic (EM) wave absorption properties with a variation of crystallization annealing temperature have been investigated in a sheet-type absorber using the alloy powder. With increasing the annealing temperature the complex permeability (), permittivity () and power absorption changed. The EM wave absorber shows the maximum permeability and permittivity after the annealing at for 1 hour, and its calculated power absorption is above 80% of input power in the frequency range over 1.5 GHz.