A thermal head producing method in which dispersion of resistance values of heating resistors in each thermal head and dispersion of the resistance values of the heating resistors per dot unit are made uniform to improve printing quality. A glaze layer is formed on a substrate and a heating resistor composed of a thin film resistor material of a mixed composition of a high melting point metal and an insulating material is formed on the glaze layer. First and second pattern conductors for providing common and separate electrodes are formed on the heating resistor and, after a protective film is formed to cover the first and second pattern conductors and the heating resistor, the heating resistor is heated so as to be a higher temperature than a dot temperature required for a printing operation. Preferably, after a resistor film formed on the glaze layer is annealed under vacuum to prepare the heating resistor, the first and second pattern conductors are formed on the heating resistor, and the protective film is formed in the same manner as described above.