A flash memory package has a controller and at least one memory including a flash memory. The controller stores received write data in a primary storage area, which is a partial storage area of the memory, sets the unit of storage area including the plurality of physical pages as the unit of collective transfer to perform collective transfer and, when a volume of data accumulated in the primary storage area is equal to or larger than the capacity of one unit of collective transfer of the flash memory, collectively transfers a volume of data corresponding to the capacity of at least one unit of collective transfer from the primary storage area to a secondary storage area, which is a partial storage area of the flash memory.