Nanoparticles of FePt were prepared in two different ionic liquids (ILs). Because IL serves not only as a solvent but also as a surfactant, the particles prepared could be dispersed stably in hexane without adding other surfactants. The size distribution of the particles was found to be narrow without depending oil a size-selection process such as centrifugation. In addition, the particle sizes and composition were found to depend on the kind of IL employed.