Japanese contributions to ITER engineering design activities are presented, together with an introduction of the objectives and design of the ITER, whose program has been carried out through international collaboration by the European Union, Japan, Russian Federation, and the United States. New technologies have been produced through the development, fabrication, and testing of scalable models in the fields of superconducting magnets, reactor structures with vacuum vessels, remote-maintenance machines, high-heat-flux plasma facing components, neutral beam injectors, high-power millimetre-wave generators, etc. As major contributions from Japan, development and testing results of a 13-T, 640-MJ, Nb3Sn pulsed magnet; an 18-deg sector of a vacuum vessel with a height of 15 m and a width of 9 m; CFC armor for a CuCrZr cooling tube that withstood 20 MW/m2; a 31 mA/cm2 negative ion beam source; a 1-MeV beam accelerator; and a 1-MW 170-GHz gyrotron are described.