A method and apparatus for generating a dewarped document using a document image captured using a camera are provided. The method includes obtaining the document image captures using the camera, extracting text lines from the document image captured using the camera, determining a projection formula to convert positions of respective points constituting the extracted text lines to coordinates projected on a plane of the dewarped document, determining a target function used to calculate a difference between text lines projected on the place of the dewarped document using the projection formula and real text lines, calculating parameters that minimize the target function, and converting the document image to the dewarped document by substituting the calculated parameters into the projection formula.