1. A storage system comprising: a data storing unit configured to store storage target data and also store address data so as to be tree-structured, the address data being based on a content and storing position of data to be referred to, and the address data referring to the storage target data or other address data; an operation log generating unit configured to generate an operation log that represents a content of an operation of storing the storage target data into the data storing unit and a content of an operation of storing the tree-structured address data referring to the storage target data into the data storing unit; and a file system committing unit configured to store the storage target data and the tree-structured address data into the data storing unit based on the operation log.