Badir al-Humaidhi on Monday took the oath of office in front of the ruler Amir Jabir al-Ahmad al-Jabir Al Sabah, according to the state-run Kuwait News Agency.
Prime Minister Sabah al-Ahmad al-Jabir Al Sabah told the Kuna agency that the former minister, Mahmud al-Nuri, had submitted his resignation about a year ago but it was not accepted.
Al-Nuri resubmitted it recently and "his health reasons left us no choice but to accept his wish," Shaikh Al Sabah said, without elaborating.
Al-Humaidhi has been director-general of the fund, the government's lending arm, since 1986.
On Wednesday, Anas al-Rshaid, a mass communications teacher at Kuwait University, was appointed information minister.
The US-educated teacher replaced Muhammad Abu al-Hassan, who resigned in January ahead of a questioning in parliament by hardline lawmakers.