A memory system includes a non-volatile memory and a controller circuit. The controller circuit is configured to carry out an atomic write operation in the non-volatile memory in response to an atomic write command, and selectively carry out one of a first operation and a second operation corresponding to address mapping between a logical address and a physical address of the non-volatile memory, along with the atomic write operation. When the first operation is selected, the controller circuit starts to update the address mapping after receiving a notification that writing of all data of the atomic write operation has been completed. When the second operation is carried out, the controller circuit starts to update the address mapping before receiving the notification.