A metal complex contains at least one ligand, each having the form of a molecule of a fullerene derivative or an anion of the fullerene derivative, where the fullerene derivative, with a solubility in n-hexane of not lower that 0.1 mg/ml at 250.degree. C., includes a fullerene skeleton and three or more organic groups attached to the fullerene skeleton, where each of the organic groups is represented by the general formula (III): --CH.sub.2--X(R.sub.2)(R.sub.3)(R.sub.4) (III) where X represents an element belonging to the group 14 in the periodic table; and R.sub.2, R.sub.3 and R.sub.4 may be the same or different and each represents a hydrogen atom, hydrocarbon group, alkoxy group or amino group.