A thermal head driver for printing out images by selectively energizing a plurality of heat-generating resistance elements which are arranged in an array, or line, to constitute a thermal head. The resistance elements are energized on an every second pixel basis or, alternatively, a plurality of resistance elements associated with odd pixels and those associated with even pixels are energized at different time points, yet a plurality of resistance elements out of each of the odd and even resistance elements are energized at the same time. Such causes any pixel to be printed out only upon the lapse of a predetermiend period of time after two immediately adjacent pixels in a line direction have been printed out.