A thermal printer comprising a printing control unit for correcting current dot printing data supplied from a host based on a previous dot history, and supplying the dot printing data to a print head unit. In accordance with the invention, the printing control unit comprises a line buffer unit for accumulating the current dot printing data; a shift register unit for getting and passing the current dot printing data and previous dot history data from the line buffer unit to a logic circuit unit, which is capable of changing data logic for driving the print head unit based on output from the shift register unit; a configuration registration unit for storing configuration data for setting the data logic of the logic circuit unit according to an energizing pattern; a node control circuit unit for switching the logic circuit unit to output data to the print head unit; and a sequencer unit for controlling the timing of the shift register units, the logic circuit units, and the node control circuit unit.