1. An information processing apparatus comprising: a processor; an image data generating unit, executed on the processor, that generates visually confirmable document image data based on an electronic document to be signed; a document image generating unit that generates a document image to be signed including the document image data and error correction data for respective digital character images contained in the document image data; a signature generating unit that generates a digital signature of the document image to be signed; a code image generating unit that generates a code image based on document-related information and information relating to the document image to be signed, the document-related information including the digital signature of the document image to be signed; and a print image generating unit that synthesizes the document image to be signed and the code image to generate a print image.