Ireland's National Treasury Management Agency (NTMA) said its €6 billion ($8.5 billion) long-term bond was heavily oversubscribed after 150 investors applied.
"The book size was just in excess of 16 billion [euros]," the NTMA's director of funding and debt management, Oliver Whelan, said.
This is the first time Ireland has tapped the debt market since it raised $500 million in 2005, which was then converted into euros.
Strong public finances, thanks to a thriving economy, meant no new bond issuance was necessary in 2006.
"We had not been in the market for a while," Mr Whelan said. "There was a scarcity element in there and investors saw it as an opportunity."
Mr Whelan said demand came mainly from European investors, especially from the United Kingdom, Germany, Austria and France as well as from Ireland. "We were very pleased with the fact that we were able to raise €6 billion. We would have been hoping to do €5 billion," he said.
Ireland is rated "AAA" by Moody's Investors Service, Standard & Poor's and Fitch Ratings.
The NTMA said the money raised by the bond, due in October 2018, would be used for general financing purposes, although agency CEO Michael Somers said last week that it would be used to pay off €6 billion worth of maturing debt.