1. A translation display apparatus comprising: a document image acquiring section that acquires a document image of a document containing a sentence composed of a plurality of lines in a first language; a character recognizing section that extracts a text area from the document image, recognizes first language characters included in the extracted text area, and specifies positions of the first language characters in the document image; a translated language character string creating section that creates a translated language character string by translating an original character string which is a first language character string including the first language characters recognized by the character recognizing section, into a second language; a translated language character string positioning section that places the translated language character string so as to be in a position which is close to the original character string and in interline space between first language character strings in the document image, based on the positions of the first language characters specified by the character recognizing section; an image creating section that creates an image of a translated sentence-added document in which the translated language character string is disposed in the document image at the position placed by the translated language character string positioning section; a display section that displays the image of the translated sentence-added document created by the image creating section; an enlargement display instruction input section that receives an instruction to enlarge and display a part of the image of the translated sentence-added document displayed on the display section; a partially-enlarged image creating section that creates a partially-enlarged image in which a part of the image of the translated sentence-added document is enlarged on the basis of the instruction inputted from the enlargement display instruction input section; and a control section that controls the image creating section and the display section, the control section controlling the image creating section to create a partial enlargement-added image which is an image obtained by superimposing the partially-enlarged image on the image of the translated sentence-added document, and controlling the display section to display the partial enlargement added image when the instruction of enlargement display is inputted from the enlargement display instruction input section.