There are provided: a distribution storage processing unit for distributing and storing a plurality of fragment data including division data obtained by dividing storage target data into a plurality of pieces and redundant data into a plurality of storing unit; an operation status detecting unit for detecting operation statuses of the respective storing unit; and a data regenerating unit for, in accordance with a result of the detection by the operation status detecting unit, when any of the storing unit goes down, regenerating the fragment data having been stored in the down storing unit based on the other fragment data stored in the other storing unit different from the down storing unit. Moreover, the data regenerating unit has a function of transferring and storing the fragment data stored in the storing unit previously scheduled to go down into the other storing unit before the storing unit goes down.