A file list generation device creates, at high speed, a list of added, changed, or deleted file data by acquiring the directory URLs of search target files from a first storage, counting the number of directories in each layer through analysis of the directory URLs, and, based on the result of the counting, determines a dividing policy to divide a scan target directory scanning operation, which is to be performed with a distributed server cluster. Directories of the search target files are divided in accordance with the determined dividing policy, and a snapshot of a current directory tree is acquired.