“Many of them buy off plan, because they’re fearless,” she added, referring to the custom of putting money down on apartments long before they are completed.

Of course, people from all over the world have been contributing to the sustained demand for apartments in Manhattan. But developers and brokers said the Irish seem to be the voracious newcomers of the moment, though their purchases have drawn less attention than previous buying sprees by the Japanese and the Saudis, who made splashes by acquiring trophy properties like Rockefeller Center and the Plaza hotel.

“Because of the weak dollar, we’re seeing a lot of European buyers and it just seems like there’s a disproportionate amount from Ireland,” said Jonathan J. Miller, president of Miller Samuel, a real estate consulting company.

Jules Demchick, who has developed several buildings in Manhattan, said the Irish are following a long parade of foreign buyers. “I’ve seen the Persians and the French and the Dutch and the Germans and the South Americans do this,” said Mr. Demchick, the president of J. D. Carlisle.

Still, he said he was surprised when Cathal McGinley, managing director of the Irish broker Kean Mahony Smith, offered to take a block of apartments in the Centria, a high-rise near Rockefeller Center, and sell them in Ireland.

After Mr. McGinley’s company quickly sold the first 25, he came back for more. Eventually, most of the units in the building were sold to Irish investors, most of whom planned to rent them.

“Bar none, the No. 1 investment strategy for an Irish person is through property,” Mr. McGinley said. “Your average Joe on the street has probably got two, three, four, five residential assets. It’s considered to be a safe play.”