According to one embodiment, a storage device includes a nonvolatile memory and a controller. The nonvolatile memory cannot overwrite data written in a memory area. The controller controls writing/reading of data to/from the nonvolatile memory in response to a request from a host device. The controller includes a garbage collection processor and a garbage collection controller. The garbage collection processor executes garbage collection to reuse a memory area on the nonvolatile memory in which unnecessary data remain. The garbage collection controller stops the garbage collection executed by the garbage collection processor when the storage device is in a loaded state equal to or less than a threshold value.