1. A storage device management device connected to a random access memory, a first storage device having a lower rewrite count upper-limit than the random access memory, and a processor, wherein; when the random access memory includes a free region sufficient to store write data which is a target of a write request from the processor, the write data is stored onto the random access memory; data on the random access memory selected in the descending order of elapsed time from the last access is sequentially copied onto the first storage device, and a region in the random access memory which has previously stored the copied data is released; when read data which is a target of a read request from the processor is stored on the random access memory, the read data is read from the random access memory to the processor; and when the read data is stored on the first storage device, the read data is copied onto the random access memory and read from the random access memory to the processor.