Aso, speaking to reporters after a cabinet meeting, said the European Stability Mechanism (ESM) plans to issue securities today for the first time since it was launched last October.
"Stability in Europe's financial situation helps stabilise currencies including the yen," Aso said.
"From this standpoint and based on Europe's further efforts on financial stability, Japan will purchase a portion of ESM bonds continuously by utilising foreign reserves."
A finance ministry official said the ESM will issue three-month bills and that Japan will decide whether to buy the first debt issue with euro from its foreign reserves after examining the issuance terms.
Japan has so far bought about €7 billion worth of bonds issued by the eurozone's temporary rescue fund, roughly 6.7% of rescue bonds on issue as at the end of last year.
Japan has been considering buying bonds to be issued by the ESM, which replaces the temporary European Financial Stability Facility (EFSF), to help resolve Europe's debt crisis and improve Japan's management of foreign reserves. The ESM bonds will rank equally with other eurozone securities held by Japan.
The ESM is designed to lend to distressed eurozone sovereigns in return for strict fiscal and structural reforms that aim to put over-indebted economies back on track.