The present invention is intended to provide a method of controlling the printing condition of a thermal print head provided with a comparatively large number of heating elements, capable of controlling the printing condition of the thermal print head by using a heating element driving circuit having a comparatively simple configuration and of dealing with increase in both printing speed and dot density. The method corrects the energizing time for each heating element (2) of a plurality of heating elements (2) of the thermal head (1) by adjusting the amount of heat to be generated by the heating elements (2) through a procedure comprising determining a plurality of logical values on the basis of the mode of energization of each heating element in the preceding printing cycles, and sequentially providing the logical values at predetermined time intervals.