Japan's 10-year government bond yield has risen to its highest since January 2014. Some investors and traders have been bidding debt yields up in expectation that the central bank will modify its monetary easing policy.
The benchmark bond's yield climbed to 0.72 percent at one stage on Tuesday.
A move by the Bank of Japan in July to let long-term yields rise slightly has damped demand for bonds.
Debt securities lose value when yields increase.
Market analysts say that investors are increasingly expecting the Bank of Japan to begin reversing monetary easing that had driven yields to record lows.
They also cited speculation that the central bank will change its negative interest rate policy sooner than some expect.