Abstract: A memory management method for a storage device having a rewritable non-volatile memory module is provided, wherein the rewritable non-volatile memory module has a plurality of physical units, and each of the physical units has a plurality of word-lines. The method includes: performing a first checking operation on a target physical unit among the physical units according to an occurrence of a specific event; and determining whether a first operation needs to be performed on valid data in the target physical unit according to a checking result of the first checking operation that corresponds to the target physical unit.