Full-scale trials were performed to qualify and optimize the manufacturing procedure of the toroidal field (TF) coil prior to the series production. In the full-scale trials, winding, reaction heat-treatment, conductor transfer, insulation, and cover plate (CP) welding trials were performed to resolve some technical issues and to demonstrate the fabrication procedure. Major requirements are: high accuracy conductor winding of 0.01%; the evaluation of the conductor elongation due to the reaction heat-treatment; the conductor transfer in a radial plate groove without adding more than 0.1% strain to the conductor; the conductor insulation without breakage of the insulation tape; and the flatness of 2 mm of the double pancake (DP) by CP welding. Then, the first TF coil fabrication has been started from March 2014. In this paper, the progress of the series production of TF coils in Japan is reported.