Kouchner arrived in Nasiriyah in southern Iraq at the start of a two-day trip during which he held talks with Vice President Adel Abdel Mahdi, said a diplomatic source who asked not to be named.
Mahdi, a Shiite Francophone who lived in exile in France, is one of the leaders of the Supreme Islamic Iraqi Council (SIIC), a key member of the governing coalition.
Kouchner attended a conference of investors at Nasiriyah university and travelled with Mahdi to the archaeological site of the ancient Sumerian civilization of Ur, 18 kilometres (11 miles) southwest of the city.
His full programme has not been disclosed for security reasons, although he was due to go to Baghdad later on Saturday for talks with President Jalal Talabani who had invited him to Iraq, the diplomatic source said.
"This visit reflects the renewed political commitment of France with regard to Iraq and the Iraqi people," the foreign ministry said in a statement issued in Paris.
During his stay, Kouchner will also have talks with Prime Minister Nuri al-Maliki and with Iraqi Foreign Minister Hoshyar Zebari.
The French minister was also expected to travel to Arbil, capital of the autonomous Kurdish region 350 kilometres (215 miles) north of Baghdad, on Sunday to open a French representative office.
France has an embassy in Baghdad, but had announced it would also open two more diplomatic offices in Iraq – one in Arbil and the other in the oil-rich port of Basra, 550 kilometres (340 miles) south of the capital.
The visit will be "an opportunity to express the availability of France to work to promote national reconciliation in Iraq," the French foreign ministry said.
Kouchner previously travelled to Baghdad in August 2007, the first visit by a member of the French government since the invasion of the country by US-led forces in 2003.
France under former president Jacques Chirac strongly opposed the invasion.
Shortly after his previous visit Kouchner had to apologise to Maliki for calling for his resignation in an interview with the American magazine Newsweek.
His latest trip comes two days after the International Compact with Iraq (ICI) conference in Stockholm where the international community hailed the Baghdad government's progress in security and reconstruction.
"The situation in Iraq is improving, but the crisis is far from over," a French diplomatic source in Paris said, adding that France was "available to host an Iraq reconciliation conference if it was deemed useful."
"It is important that the international community, particularly the European Union, rise to the occasion to help Iraqis," added the source, noting that Paris will have the rotating EU presidency in the second half of this year.
Kouchner arrived in the country from Jordan where he said on Friday that France was ready to receive 500 refugees from Iraq "as a first step."