The invention discloses a flash memory apparatus, including a plurality of blocks and a memory controller. The blocks include a first block, wherein the first block includes a first page. The memory controller receives a first data to be written into the first page of the first block. When the first page has already been written to, the memory controller further selects one of the blocks as a first cache block, writes the first data into a first cache page of the first cache block and records the number of the first block and the number of the first page into the first cache page. The memory controller further updates the first block according to the number of the first block and the number of the first page recorded in the first cache page when receiving an update command.