Ultrathin oxide films have attracted a great deal of interest due to their importance in both fundamental and technological applications. It was recently reported that the charge state of metal atoms on ultrathin oxide films, such as MgO/Ag(001), plays an important role in various chemical reactions. In this work, we investigate the adsorption properties of metal atoms deposited on ultrathin MgO/Fe(001) films by carrying out ab initio electronic structure calculations based on the density functional theory. Calculations of Au/MgO/Fe(001) shows that the Au atom prefers to adsorb on the surface hollow site contrary to the most favorable surface O site for Au adsorbed on MgO(001). With the presence of Fe support, charge transfer to the Au atom leads to the negative charging of Au, as in Au/MgO/Ag(001). For Pd/MgO/Fe(001), it was also found that negative charging occurs even for Pd with lower electron affinity than Au. Interestingly, Pd becomes spin-polarized with the presence of the magnetic Fe substrate contrary to Pd/MgO/Ag(001). Present calculations clearly suggest that the magnetic Fe substrate supporting the MgO films can offer a new way to modify the spin states, as well as the charge states, for metal atoms adsorbed on ultrathin oxide films.