Provided is an operating method of a memory system which includes a plurality of nonvolatile memory devices; and a controller configured to control the nonvolatile memory devices to store data therein. The operating method may include: receiving, by the controller, a write request for logical addresses from a host device; determining, by the controller, whether a start logical address among the logical addresses satisfies an alignment condition, the start logical address indicating where a write operation is to be performed in a target nonvolatile memory device among the nonvolatile memory devices; determining, by the controller, target data by determining one or more target logical addresses among the logical addresses through an alignment operation, when the start logical address does not satisfy the alignment condition; and controlling, by the controller, the target nonvolatile memory device to perform the write operation on the target data.