A memory system includes a memory device suitable for storing L2P map data including a logical address of an external device and a physical address of a memory device corresponding to the logical address, and a controller suitable for storing at least a portion of the L2P map data and state information of the L2P map data, and controlling data input/output of the memory device, wherein, when a write request, write data and a first physical address with a first logical address are received from an external device, the controller performs a write operation for the write request on a second physical address to which a logical address is not assigned, and invalidates the first physical address, and the controller transmits a first acknowledgement, which does not include the second physical address, to the external device, after completely performing the write operation.