1. A storage system, comprising: a data writing unit for storing actual data configuring storage data to be written into a storage device and, every time a content of the storage data is updated, newly storing actual data configuring the updated storage data into the storage device; and a data specifying unit for specifying latest storage data among same storage data stored in the storage device, wherein: the data writing unit is configured to store actual data configuring the storage data into the storage device in association with update information whose value increases by 1 every time the storage data is updated; and the data specifying unit is configured to check whether the update information whose value is 2 i (i represents an integer equal to or more than 0) exists in the storage device in an increasing order of a value of i, specify a largest value of the existing update information from among values between a largest value of 2 i that the corresponding update information exists and a value of 2 i+1 , and specify storage data configured by actual data associated with the largest value of the update information, as the latest storage data.