A storage device according to some aspects of the invention includes a communication unit configured to perform processing for communication with a host apparatus; a storage unit configured to have a first memory area and a second memory area that store therein received data from the host apparatus, and memory area selection information; a memory control unit configured to select one of the first memory area and the second memory area as a memory area for reading, select the other one thereof as a memory area for writing, and perform control of reading and writing; and an increment determination unit configured to compare a value of data having been read out from the memory area for reading by the memory control unit and a value of the received data to determine a magnitude relation therebetween.