This book describes the transmutation performance of minor actinides in fast reactors from the fundamental aspects such as meanings of minor actinides to practical aspects such as of core designs of minor actinides transmutation fast reactors. The physical meaning of the transmutation of minor actinides is presented and one can understand that the MA transmutation consists of two terms; the overall fission term and the net plutonium production term. MA transmutation performances in MA transmutation fast reactors is described together with the analyses of core safety.