The effect of Fe atoms coadsorption on the diffusion of adsorbed Ni atoms at Si(111) surface has been studied by low energy electron diffraction and Auger electron spectroscopy. It has been shown that the coadsorption of submonolayer quantities of Fe increases markedly the Ni surface diffusion which is most conspicuous in the 750-600 degrees C temperature range. It has been also shown that the dependence of the Ni surface diffusion coefficients versus temperature is a nonmonotonous function.