A data storage apparatus includes storage divided into unit physical regions and having data stored therein, a buffer memory having buffer memory regions loaded with a map table comprising map data respectively indicating connection information between logical addresses of a host and start physical addresses for the unit physical regions, and a controller configured to: control data input and output to and from the storage according to a request of a host, to read, based on a map table address corresponding to a logical address included in the request, the map data for the logical address from the buffer memory, and to remap the map data by merging source map data of a buffer memory region having a number of errors equal to or greater than a threshold value with victim map data of a buffer memory region having a number of errors less than the threshold value.