Provided is a storage system capable of holding data by associating main data for long-term retention with sub data for maintaining its readability. The storage system: stores first data in a first location within a storage area upon reception of a storage request for the first data with a first file identifier being specified; holds information for associating the first file identifier, the first location, a retention period of the data, and first version information with one another; stores second data in a second location within the storage area upon reception of a storage request for the second data with the first file identifier and second version information being specified; holds information for associating the first file identifier, the second location, and the second version information with one another; and inhibits the first data and the second data from being changed before elapse of the retention period of the data.