Disclosed is a digital document management program capable of achieving a third-party certification of document information with reduced amount of meta data.At the registration time of new document information, the digital document management program manages a digital signature created in association with document information. At the correction time of the document information, the program acquires partial identification information related to a corrected part of the document information before correction, creates a digital signature to be appended to the corrected document information, and manages the digital signature and partial identification information related to the corrected part of the document information in association with the corrected document information. At the verification time, the program uses partial identification information, the partial identification information corresponding to a corrected part of the document information before correction, and digital signature to perform verification.