The yield touched a new low of 1.378 percent, according to Reuters data, dropping below the previous trough of 1.3810 struck in July 2012.
Concerns about growth, not least as a result of Britain's vote last month to leave the European Union, and the prospect of easier monetary policy, have driven investors to seek low-risk government debt.
This has pushed yields in Germany, Japan and Switzerland to a series of new lows in recent days.