According to one embodiment, a cache memory system includes a cache memory and a cache controller. The cache memory can store first data to be read or written by a processor. The cache controller is configured to execute a refresh. The refresh includes reading the first data stored in the cache memory and writing the read first data to the cache memory. When executing the refresh, the cache controller is configured to exchange the first data stored in a first area of the cache memory for second data stored in a second area of the cache memory.