A semiconductor file system features a first nonvolatile memory electrically erasable, a second nonvolatile memory not electrically erasable, a volatile memory, a controller, and a control section which controls the controller wherein a physical address corresponding to a logical address specified from an external system is accessed. The first nonvolatile memory stores data for the external system to perform operations, first management information indicating correspondence between physical and logical addresses, and second management information indicating a state of the first nonvolatile memory. The second nonvolatile memory previously stores interface information. The controller determines a physical sector address. The control section is for controlling input/output of data from/to the external system and for temporarily storing write data into the first nonvolatile memory from the external system in the volatile memory and then transferring the write data from the volatile memory to the first nonvolatile memory.