HTML data that contains at least a set of reference data (URL) of a visualized image containing characters, reference data (URL) of an un-visualized background image containing no characters whose display position is set to an area superimposed on the image, and un-visualized text data whose display position is set to an area superimposed on the background image is stored in a web DB, and the un-visualized background image data and the text data are visualized and the visualized image data is un-visualized in a translation process.