A storage system comprising a plurality of storing means and a data processing means configured to store data into the plurality of storing means and retrieve the data stored in the storing means, wherein: the data processing means includes: an identification information providing means configured to provide identification information distinguishing a group of data requested to be stored, to the group of data; a data set generating means configured to generate division data by dividing storage target data that is part of the group of data into a plurality of pieces and also generate redundant data for restoring the storage target data, thereby generating a data set composed of a plurality of fragment data that are the division data and the redundant data; and a distribution storage controlling means configured to distribute the fragment data composing the data set and store the fragment data, respectively, in same logical storing positions within storage regions formed in the respective storing means, thereby storing the storage target data; and the distribution storage controlling means is configured to, before storing into the storing means, store, into buffer memories corresponding to the identification information set for the storage regions, respectively, the fragment data composing respective data sets corresponding to a plurality of storage target data included in the group of data provided with the identification information that is the same as the identification information corresponding to the buffer memories, store the fragment data having a predetermined capacity included in the group of data provided with the same identification information such that storing positions in the buffer memories become contiguous, and store all of the fragment data stored in all of the respective buffer memories corresponding to the same identification information into the respective storage regions formed in the respective storing means corresponding to the respective buffer memories, at the same timing. an identification information providing means configured to provide identification information distinguishing a group of data requested to be stored, to the group of data; a data set generating means configured to generate division data by dividing storage target data that is part of the group of data into a plurality of pieces and also generate redundant data for restoring the storage target data, thereby generating a data set composed of a plurality of fragment data that are the division data and the redundant data; and a distribution storage controlling means configured to distribute the fragment data composing the data set and store the fragment data, respectively, in same logical storing positions within storage regions formed in the respective storing means, thereby storing the storage target data; and the distribution storage controlling means is configured to, before storing into the storing means, store, into buffer memories corresponding to the identification information set for the storage regions, respectively, the fragment data composing respective data sets corresponding to a plurality of storage target data included in the group of data provided with the identification information that is the same as the identification information corresponding to the buffer memories, store the fragment data having a predetermined capacity included in the group of data provided with the same identification information such that storing positions in the buffer memories become contiguous, and store all of the fragment data stored in all of the respective buffer memories corresponding to the same identification information into the respective storage regions formed in the respective storing means corresponding to the respective buffer memories, at the same timing.