A data backup method and a data recovery method are provided. The data backup method includes: updating a main information table and a sub information table and generating physical unit information according to an erase count and a physical unit status of a physical unit; writing the physical unit information into the physical unit before writing data into the empty physical unit; writing the main information table and the sub information table into a rewritable non-volatile memory module according to corresponding conditions. The data recovery method includes: writing a latest main information table stored in a rewritable non-volatile memory module into a memory; updating the main information table in the memory according to a sub information table which is newer than the main information table; and updating the main information table in the memory according to physical unit information which is newer than the sub information table.