Abstract: Disclosed herein is a system and method for protecting digital works on a communication network. The work protection system includes one or more intermediate servers, one or more list provision servers and a work protection server. The intermediate servers perform intermediation of data shared. The list provision servers provide list information of the intermediate servers. The work protection server connects with a corresponding intermediate server, searches for shared digital works, calculates a saturation or dilution by examining the presence of identifiers, generates file and connection information about digital files to be shared, and causes the previously stored files of digital works to be protected to be shared.