Mr Marshall says the "chaotic" organisation of the public sector under Labor has to stop.

"We've already said we are going to have an arrangement where chief executives report to a single minister," he told reporters on Monday.

"One of the critical things for us is making sure we have a government that takes responsibility.

"We have a situation at the moment where chief executives answer to up to six ministers and that's not good enough."

Mr Marshall said which senior public servants will go under his government is yet to be determined.

But he said the Liberals considered the public service to be a "great asset" and his government would work with it constructively.

Mr Marshall was officially sworn in as South Australia's 46th premier on Monday in a private ceremony at Government House.

Immediately after he said it was both a great honour and a great responsibility to lead the state.

"It's a great opportunity. I'm really looking forward to it," he said as he left.

Also sworn in were new Deputy Premier Vickie Chapman and Treasurer Rob Lucas.

Ms Chapman becomes the first woman to be South Australia's deputy premier, while for Mr Lucas, it's a return to the role he held in the previous Liberal administration 16 years ago.

The rest of the premier's new cabinet will take their oaths on Thursday.

Monday's ceremony came after the new premier visited Governor Hieu Van Le on Sunday to inform him of the election result and that he could form a government.

The Liberals will finish with at least 24 seats in the new parliament and are favoured to pick up at least one of the two still in doubt.

Labor should finish with 19 and there will be three independents.

The issue of the Labor leadership could also be decided this week with former health minister Peter Malinauskas favoured to replace Jay Weatherill who announced his decision to stand down on Sunday.

Australian Associated Press