R&D needs for a neutrino factory

The R&D needs for a neutrino factory, based on a muon storage ring, are presented. Such a neutrino factory consists of several modules. All these modules must be developed, namely: intense proton source, pion production target and collection system, ionization cooling, acceleration and storage of the muons. R&D on these modules will be discussed in terms of theory and simulation, engineering prototypes, and experiments in particle beams.