PURPOSE: To enhance image quality by eliminating the generation of a dent on a recording medium due to the edge in a sub-scanning direction of a heating resistor by extremely making the width of the heating resistor in the sub- scanning direction larger than the interval between electrodes and reducing the internal strain of the heating resistor.

CONSTITUTION: A thermal head has a common electrode 2, a plurality of individual electrodes 3 mutually independently arranged in opposed relation to the common electrode in a main scanning direction, the heating registers 4 bridging the common electrode 2 and the individual electrodes 3 in a sub-scanning direction and the protective layer 6 covering the common electrode 2, the individual electrodes 3 and the heating resistors 4. Dummy resistors 5a, 5b are provided on the common electrode 2 and the individual electrodes 3 so as to be adjacent to the end parts of the heating resistors 4 in the sub-scanning direction.