An operating method of a storage device which includes a first nonvolatile memory device and a second nonvolatile memory device includes detecting sudden power-off, suspending an operation being performed in the first nonvolatile memory device, in response to the detected sudden power-off, writing suspension information about the suspended operation into the second nonvolatile memory device, and performing a block management operation on the first nonvolatile memory device based on the suspension information written into the second nonvolatile memory device, in power-up after the sudden power-off.