To provide a thermal head driving device capable of executing smooth gamma conversion by correcting an energy quantity in one gradation printing to be applied to a thermal head without reducing the number of gradations included in input data, and of representing an output image by the number of gradations in the input data, thereby improving image quality.

This thermal head driving device drives a plurality of heating resistor elements forming a thermal head 108 in accordance with multi-value printing data. The device comprises a ROM 105 that stores printing energy correction data for making a brightness characteristic or a density characteristic of an image printed and formed by the thermal head 108 to be a predetermined characteristic and a strobe generator 106 that varies a printing energy correction value of one gradation level which is determined based on the printing energy correction data in the ROM 105 corresponding to the gradation level in the printing executed by the thermal head 108.