Various kinds of Fe-R amorphous alloys have been prepared by a high-rate dc sputtering method in order to study the Curie temperature T c as a function of the de Gennes factor G for Fe 2 R, and to the difference of the density between amorphous and crystalline states. The exchange interaction between Fe-Fe in iron-light rare earth amorphous alloy systems of Fe 2 R persists and their Curie temperatures are lower than those crystalline counterparts. It should be noted that T c of Fe 2 Ce in the both states is much lower than that expected from the G vs. T c curve due to the valence fluctuation. In iron-heavy rare earth amorphous alloys of Fe 2 R, Fe-Fe exchange interaction becomes zero, being consistent with the results previously reported. The concentration dependence of the room temperature density shows a distinct anomaly around the composition corresponding to Fe 2 R. This difference between these two states is attributed to the denser packing structure of the Laves compounds. With increasing Ce content, the density of Fe-Ce amorphous alloy system increases although the density of Ce is lighter than that of Fe. This behavior is caused by the valence fluctuation of Ce in the alloy system.