Spokesman Martin Jaeger said the woman has been missing since 25 November. He gave no further details about her.
Germany's ARD television reported that the woman and her driver have been taken hostage by militants. The station said it had obtained a video allegedly showing pictures of the woman, and that her kidnappers have threatened to kill her unless Germany stops all cooperation with the Iraqi government.
It was not immediately clear what the woman was doing in Iraq.
The report of the missing German follows reports that four foreign aid workers -- two Canadians, a Briton, and an American -- have also disappeared in Iraq.
Yesterday in Iraq, two Britons were reported killed in Baghdad when gunmen ambushed a bus carrying British Muslims to Shi'ite shrines.