Japanese activities on fusion structural materials R & D have been well organized under the coordination of university programs and JAERI/NIMS programs more than two decades. Where, two categories of structural materials have been studied, those are; reduced activation martensitic/ferritic steels (RAFs) as reference material and vanadium alloys and SiC/SiC composite materials as advanced materials. The R & D histories of these candidate materials and the present status in Japan are reviewed with the emphasis on materials behavior under radiation damage. The on-going Japan-USA collaborations on blanket engineering and materials, JUPITER-II Program and on neutron radiation effects, JAERI/ORNL Phase IV and V are also presented.