[en] In Japan, the development and utilization of atomic energy are promoted as the main supply source of the substitute energy to petroleum. The scale of nuclear power generation in Japan is 27.88 million kW of 35 plants in operation, under construction and in planning stage. The perfectness is expected regarding the security of nuclear power plants by the safety of reactors themselves, the installation of technological safety devices and the regulations of the relevant laws, but trivial troubles occur frequently, and the fear of residents cannot be wiped out. The proving test on the reliability of nuclear power generation facilities has been carried out since 1975, and in this paper, the proving test on the reliability of steam generators is outlined. The necessity, the outline of the experimental program and the contents of the proving test are described. The thermal flow test with a large steam generator, the thermal flow test with freon, the rupture test on heat transfer tubes, the integral corrosion test on a steam generator, the simulation test of partial corrosion and so on have been carried out. These tests are scheduled to last for six years since 1975, and the state of progress in every year is reported. The useful data on corrosion, rupture, thermal flow behavior and others have been collected, and the generalizing evaluation of the results based on the collected data is to be made in 1980, but the results on partial corrosion are summarized. (Kako, I.)