The mobility data of Mn that is considered important among the Fe-base alloy system are assessed. The mobility parameters were obtained on the Fe-Mn and Ni-Mn binary systems of which experimental diffusion data were available. The parameters of the self diffusivity and the tracer diffusivity were assessed, and the interdiffusivity have been optimized by using them. Comparison between the experimental data and the optimized results has been made in various compositions and temperatures.