Design study of high energy proton FFAG accelerator has been carried out at Kyoto University Research Reactor (KURRI) for the next generation ADSR experiment where the proton beam energy covers up to 700MeV. The scaling type of FFAG with spiral sectors was employed. Details of the design issue concerning about the operational working points, lattice parameters and 3D magnet modeling / optimization are described. Also, some possibilities to apply this design to carbon therapy accelerators are presented.