Bonded soft ferrite has been expected for many applications because of its low cost and well adaptability for the complicated shape. However, since the effective permeability is too low due to the mixture of ferrite powder and resin, the remaining problem is to enhance the permeability. So, the present study is to establish a method to estimate the induction together with the permeability of the powder material and to effectively investigate bonded soft NiCuZn ferrite materials. As a result, it has been found that the sintering temperature of the ferrite powder is essential to attain high inductance, and the broader distribution of pariticle size of ferrite powder results in the higher inductance.