According to one embodiment, a command management device includes a command buffer, a free address register and a FIFO unit with entries. The command buffer stores commands received from a host. The entries include address sections configured to store addresses of the areas in the command buffer in which the respective commands are stored. The address sections are connected together like a ring. Each of the address sections includes a substitute module configured to substitute either the free address held in the free address register or a second address stored in the address section preceding the each of the address sections for a first address stored in the each of the address sections.