A storage system includes a first storage device, and a second storage device retrieving stored data at higher speeds than the first storage device. The storage system further includes a feature calculation unit calculating feature data based on a data content of storage target data, a data management unit storing the storage target data and managing a storing position thereof based on the feature data calculated from the storage target data, and a duplication determination unit determining whether or not the same storage target data as the storage target data to be newly stored is already stored in the first storage device. In a case that the same storage target data as the storage target data to be newly stored is already stored in the first storage device, the data management unit stores the storage target data already stored in the first storage device into the second device.