A storage device includes one or more nonvolatile memories, and a memory controller that controls the nonvolatile memories such that write data of data streams is stored in the nonvolatile memories. The data streams have a first number of requested stream identifiers provided from a host. The memory controller includes a write amount manager that manages information about a data amount of each of the data streams having the requested stream identifiers, a stream manager that maps the first number of the requested stream identifiers with a second number of processing stream identifiers, depending on the information associated with the data amount, such that the data streams are provided to the nonvolatile memories according to the second number of processing stream identifiers, and a mapping manager that manages information about mapping between the first number of the requested stream identifiers and the second number of the processing stream identifiers.