Palestinian security officials named the man as Omar Abdulrazek, a senior Hamas member whom the group appointed finance minister after they won legislative elections in 2006.
They said he was arrested early Tuesday at his home in Salfit, south of the West Bank city of Nablus. An Israeli military spokesman confirmed the arrest of a Hamas member in Salfit, but named him as Omar Mahmud Matar.
The spokesman, who spoke on condition of anonymity, said the arrest was coordinated with the Israeli Security Agency, also known as the Shabak.
He declined to say why the Hamas member was arrested.
Israel has in recent months rearrested several of the dozens of Hamas lawmakers it detained in June 2006 following the kidnap of Israeli soldier Gilad Shalit, who remains in captivity in Gaza.
Abdulrazek was detained in June 2006 and released more than two years later in August 2008.
In total, Israel arrested 64 Hamas members after the kidnap of Shalit on 25 June 2006. With Abdelrazek's detention, at least six of those arrested then are back in Israeli custody.
Hamas, which rules the Gaza Strip, has demanded the release of hundreds of Palestinians, including several convicted of deadly attacks, in exchange for Shalit.
Talks between Hamas and Israel over Shalit, mediated by Egypt and Germany, ground to a halt in late 2009.
Israel and Hamas blame each other for failing to reach a deal.