An aspect of the present embodiment, there is provided a memory system including a nonvolatile memory area, a first interface be connected to a first host device, a second interface connected to a second host device, and a controller controlling the first interface such that the first device is configured to prohibit to write data into the nonvolatile memory area on a basis of a command provided from the second host device before the second host device writes data into the nonvolatile memory area through the second interface, wherein the first interface notices an error to the first host device when the first device writes data into the nonvolatile memory area, and the second host device transmits data from an portion not to be written in the nonvolatile memory area to the first host.