[en] To understand the long-term leach behavior of a borosilicate waste glass in a repository, the leaching experiment with three kinds of simulated borosilicate waste glasses has been carried out since the middle of 1997. The five years results indicate that a boron would be applied as an indicator of a long-term leachning of their borosilicate waste glasses and that their long-term leach rates have a tendency to be close to about 0.03g/m²-day even though their compositions and their ratios of the surface area to the volume of leachate are different