PURPOSE: To automatically correct uneven temperature of heat generated between heat generating elements by differentiating the electric resistance value at least between heat generating elements at the end of a train of thermal print heads arrayed as such and those at the center thereof.

CONSTITUTION: Power is supplied to heat generating elements 1 made of material such as Ta2Na and Ta-SiC from a lead 2. The heat generating elements 1 are arranged zigzag in a pattern design. As the electric resistance value of each heat generating element 1 is proportional to the extension distance of the zigzag, it can be set as desired at the pattern designing. With due consideration given to thermal interference between the heat generating elements, those patterns are selected that allows the interval to be held sufficiently between adjacent heat generating elements. At the pattern designing, a plurality of heat generating elements 1 with the electric resistance value set as specified are arrayed in a train to construct a thermal print head. The electric resistance value of the thermal print head is differentiated between the center and the end of the train.