A memory system includes a nonvolatile memory set including a nonvolatile memory; and a memory controller configured to control the nonvolatile memory set. The memory controller may write data to a memory block in a target memory block pool in the nonvolatile memory set during a target time period existing between a time at which an operation mode for the nonvolatile memory set is changed from a second operation mode to a first operation mode and a time at which a command including information indicating that a host expects a requested operation to be performed in the first operation mode is received from the host, prevent execution of a background operation for the nonvolatile memory set, when the operation mode is the first operation mode, and control a background operation for the nonvolatile memory set to be executable, when the operation mode is the second operation mode.