Japan is expected to make a major contribution to the procurement of the ITER superconducting magnet system, including the TF coil windings and structures, and conductors for the TF coil and CS. JAEA has started preparation activities for the ITER construction in tight collaboration with industries. These activities include manufacturing studies to identify detailed fabrication processes and tools for critical components, and manufacturing demonstrations at full scale level based on the studies. So far, high-performance Nb 3Sn strands that satisfy the ITER requirements have been developed and full scale trial fabrications of new cryogenic materials, such as JJ1 and strengthened 316LN, have successfully been performed for TF coil case and radial plates. Results from these activities will provide a firm technical basis to achieve required performance of the magnets while maintaining both project schedule and cost.