1. A document classification and inspection system that obtains digital information including document information configured by a plurality of documents recorded in a plurality of computers or servers and assigns to one or more of the documents a classification code indicating the degree of relevance of the documents to an inspection matter, the system comprising; at least one processor; a memory, wherein the memory has stored thereon instructions that, when executed by the processor, causes the processor to: extract a document from the document information; calculate, with respect to the extracted document, a score indicating the strength of connection of the document and the classification code in a time series manner; detect a time-series score change from the calculated score; and inspect and determine the degree of relevance between the inspection matter and the extracted document from the detected time-series score change.