The present invention relates to apparatus and method for producing a document verifiable for its forgery or alteration, and apparatus and method for authenticating the document. A barcode is generated based on the information included in the document, and also watermark is generated based on the information included in the document. The generated barcode and watermark are combined, and the combined barcode and watermark are inserted in the document so as to produce the document. When authenticating the document, the document is detected so as to extract the barcode inserted in the document and the information included in the extracted barcode and the information included in the document are compared, and also the document is detected so as to extract the watermark inserted in the document and the information included in the extracted watermark and the information included in the document are compared. According to the present invention, it is possible to prevent forgery or alteration of the document produced on-line and off-line when such document is distributed on-line or off-line. It is also possible to verify whether the document has been forged or altered, and also to verify the forgery or alteration of the barcode itself.