An apparatus and method for authoring multimedia documents are provided. The apparatus includes a template document floating field detector for detecting a floating field of a template document, which is an incomplete multimedia document having a fixed field and the floating field, by parsing a control document including information identifying the floating field and a list of selectable objects; a control document provider for rendering and outputting the control document; a user selection information receiving unit for receiving information selected by a user with respect to the control document output from the control document provider; and a multimedia document finisher for completing the template document as a multimedia document by fixing the detected floating field to be an object designated by the information selected by the user among the list of selectable objects, when the information selected by the user is received.