A flash memory system is disclosed. The flash memory system includes a flash memory comprising more than one physical block and more than one page, where each page can be in an enabled state, a blank state or a disabled state. In use, a merge control section reads data on an enabled page from a predetermined physical block using a read section, and writes the data onto a blank page using a write section, thereby copying the data on the enabled page onto the blank page. A merge control section then disables the enabled page using a page-disabling section. When the copying of the data from all the enabled pages in the predetermined physical block is finished, the merge control section collectively erases all the data in the physical block using an erase section.