A controller for controlling a non-volatile memory apparatus including page groups each including a plurality of pages is configured to select a target page group from the page groups, wherein the target page group includes at least one invalid page and at least one valid page, select, as a target threshold voltage distribution, a lower threshold voltage distribution of two adjacent threshold voltage distributions distinguished by an invalid read voltage, wherein the invalid read voltage is a read voltage for distinguishing between data stored in the invalid page, select, as a target memory cell, a memory cell located in the target threshold voltage distribution among a plurality of memory cells configuring the target page group, and control the non-volatile memory apparatus to perform an adjustment program operation for raising a threshold voltage of the target memory cell as much as a first voltage.