A nonvolatile storage device includes a controller and a nonvolatile memory. The controller has: a logical-physical address conversion part for converting a logical address designated by a host device into a physical address; and a boot code address conversion part for converting boot code address information designated by the host device into a physical address. After the power-on and before the logical-physical address conversion part becomes usable, a boot code is read from a part of region which can be accessed by designating a logical address from the host device by designating the boot code address information from the outside. Thus, it is possible to rapidly start the nonvolatile memory system after the power-on. In the state where the logical-physical address conversion part can be used, data-reading and data-writing are carried out by designating a logical address from the host device.