The storage control device of the present invention is able to perform input and output of data between blocks whose size is different with good efficiency. The size of extended logical blocks, which are units of data input and output within a storage control device, and the size of physical blocks, which are provided within the storage device, are different from one another. A write object range generation unit reads out both of the extended logical blocks which are adjacent to the write data, and creates a write object range by linking them to the write data. An assurance code checking unit checks a corresponding assurance code for each of these extended logical blocks. And a block size adjustment unit deletes superfluous data from the adjacent blocks, and adjusts the size of the write object range, so that it becomes an integral multiple of the size of the physical blocks.