The dependence of magnetic properties on the carrier concentration for Ge1-xMnxTe films prepared by ionized-cluster beam technique has been studied to clarify the mechanism of carrier-induced ferromagnetism. The experimental results suggest that the cluster of spins aligned by short-range ferromagnetic interaction tends to be formed for samples with the lower carrier concentration than the critical value for the occurrence of homogeneous ferromagnetic order. With increasing carrier concentration, the long-range ferromagnetic interaction grows. The magnetotransport properties of Ge1-xMnxTe films are found closely related to its magnetic properties, indicating carrier-enhanced ferromagnetic effects. © 2002 American Institute of Physics.