11. A forensic method which acquires digital information recorded on a plurality of computers or a server to analyze the acquired digital information, comprising: a step of acquiring digital information containing digital document information composed of a plurality of document files, and user information about user utilizing the plurality of computers or the server; a step of recording digital information acquired by the digital information acquiring unit; a step of displaying the recorded digital information; a step of setting user-specifying information showing which one of users contained in the user information each of the plurality of document files is related with, wherein setting the user-specifying information includes setting ranking information showing a first relative degree of relationship a first user from among the users has with litigation, and showing a second relative degree of relationship a second user from among the users has with the litigation; a step of setting the recording unit to record the set user-specifying information; a step of selecting at least one user; a step of searching a document file where user-specifying information corresponding to the selected user was set; a step of providing a book-mark function allowing book-mark search for material set with a hierarchy structure book-mark; a step of highlighting on a display a searched word or phrase; a step of setting one or more access rights for each of a plurality of accounts associated with a browser, wherein the step of setting the one or more rights includes setting a manager right associated with the browser; a step of producing statistical data represented by data size for each data format of the acquired digital document information or statistical data represented by data size for each data format of the digital document information; a step of selecting a kind of file to be searched; a step of preserving a selected file as a separate file; a step of setting additional information showing whether or not the searched document file is related with the litigation, wherein the additional information includes at least one of a first tag indicating that the searched document file is related with the litigation, a second tag indicating that the searched document file is potentially related with the litigation, and a third tag indicating that the searched document file is not related with the litigation; and a step of outputting a document file related with the litigation based upon the first relative degree of relationship the first user from among the users has with the litigation, the second relative degree of relationship the second user from among the users has with the litigation, and the at least one of the first tag indicating that the searched document file is related with the litigation, the second tag indicating that the searched document file is potentially related with the litigation, and the third tag indicating that the searched document file is not related with the litigation.
11. A forensic method which acquires digital information recorded on a plurality of computers or a server to analyze the acquired digital information, comprising: a step of acquiring digital information containing digital document information composed of a plurality of document files, and user information about user utilizing the plurality of computers or the server; a step of recording digital information acquired by the digital information acquiring unit; a step of displaying the recorded digital information; a step of setting user-specifying information showing which one of users contained in the user information each of the plurality of document files is related with, wherein setting the user-specifying information includes setting ranking information showing a first relative degree of relationship a first user from among the users has with litigation, and showing a second relative degree of relationship a second user from among the users has with the litigation; a step of setting the recording unit to record the set user-specifying information; a step of selecting at least one user; a step of searching a document file where user-specifying information corresponding to the selected user was set; a step of providing a book-mark function allowing book-mark search for material set with a hierarchy structure book-mark; a step of highlighting on a display a searched word or phrase; a step of setting one or more access rights for each of a plurality of accounts associated with a browser, wherein the step of setting the one or more rights includes setting a manager right associated with the browser; a step of producing statistical data represented by data size for each data format of the acquired digital document information or statistical data represented by data size for each data format of the digital document information; a step of selecting a kind of file to be searched; a step of preserving a selected file as a separate file; a step of setting additional information showing whether or not the searched document file is related with the litigation, wherein the additional information includes at least one of a first tag indicating that the searched document file is related with the litigation, a second tag indicating that the searched document file is potentially related with the litigation, and a third tag indicating that the searched document file is not related with the litigation; and a step of outputting a document file related with the litigation based upon the first relative degree of relationship the first user from among the users has with the litigation, the second relative degree of relationship the second user from among the users has with the litigation, and the at least one of the first tag indicating that the searched document file is related with the litigation, the second tag indicating that the searched document file is potentially related with the litigation, and the third tag indicating that the searched document file is not related with the litigation. 16. The method according to claim 11 , wherein the step of setting the one or more rights includes setting a browsing-only right associated with the browser.