"It would not be appropriate for the board to comment on a case that is currently before the French judiciary. However, the board is confident that she will be able to effectively carry out her duties as managing director," the International Monetary Fund Executive Board said in a statement.
The board said it had already reviewed the issues involved in the case when it considered the former French Finance Minister's candidacy in June.
Lagarde, 55, took over as managing director from Dominique Strauss-Kahn in July, following his arrest in May on charges of the attempted rape of a New York hotel maid.
Earlier, a French court ordered a probe for embezzlement and other fraud-related charges against Lagarde dating to when she was finance minister.
Lagarde is accused of wrongly pressing a bank to enter binding arbitration over a dispute with a businessman who supported President Nicolas Sarkozy's election campaign.
Prosecutors say Lagarde abused her authority by approving a 285m-euro (USD 406 million) payment to businessman Bernard Tapie, a former left-wing minister who switched sides to support Sarkozy in the 2007 presidential election.
Lagarde has denied any wrongdoing in the case. Lagarde's lawyer, Yves Repiquet, said the court's decision would not affect her work. "This procedure is in no way incompatible with the current functions of the managing director of the IMF," he said.
Repiquet described the inquiry as "suspicion abusively cast on Christine Lagarde by a handful of opposition members of parliament for political ends".