According to one embodiment, a memory system includes a controller. The controller controls throttling to make a performance value of the memory system fall between a first performance value and a second performance value. The throttling limits the number of times of accesses per unit time to a nonvolatile memory. The first performance value is calculated based on a third performance value of the memory system and is greater than the third performance value. The third performance value is a value which is expected to be reached at a time when a first period has elapsed since the memory system started being used if throttling is not performed. The second performance value is provided between the first performance value and the third performance value.