IMF chief Christine Lagarde said Japan should make reducing its mammoth public debt a priority, during a visit to Tokyo where she met Japanese officials.
"We shared the view that the priorities going forward are the swift implementation of reconstruction spending, and the adoption of a strong medium-term plan to reduce public debt," she said in a press release on Saturday.
Japan's public debt is one of the world's largest at more than 200 percent of GDP, after years of pump-priming measures by governments trying in vain to arrest the economy's long decline.
Much of government spending is swallowed up by a social security system catering to a rapidly ageing population, while entrenched deflation and the feeble economy have made it hard for lawmakers to curb borrowing.
Lagarde earlier held meetings with Japanese finance minister Jun Azumi, financial services minister Shozaburo Jimi and Bank of Japan Governor Masaaki Shirakawa, on a trip that saw her visit Russia and China earlier this week.