Provided is a computer system including: a client computer; a storage system coupled to the client computer via a network; a folder deciding module; and a file storage module, in which each of a plurality of files is stored in one of a plurality of folders; the client computer receives an instruction to store a file; the folder deciding module judges how strongly the plurality of folders are each related to the designated file based on a matching degree between each of the plurality of files stored in the plurality of folders and the designated file; and the file storage module stores the designated file in one of the plurality of folders that has been judged to be most strongly related to the designated file. According to this invention, a created file is stored in a suitable folder so that the file can easily be found by the user.