In an information processing device, a reading unit reads in a filled-in document. A recognition unit recognizes a standard document type and an information structure of the document. A storage unit stores content filled in on the document. If the read-in document is not a most recent version, a comparing unit compares the information structure of the most recent version of a preregistered standard document type corresponding to the recognized standard document type to the recognized information structure. A generation unit generates a differential document of the modified information structure, according to a result of the comparison. An output unit outputs the generated differential document. If a filled-in differential document is read in, a merge unit merges filled-in content on the differential document with filled-in content on the stored document, and the storage unit replaces the already-stored content with the merged content.