PURPOSE: To improve print quality by polishing the crown of partially glazed portion on an insulating substrate and flattening the partially glazed portion corresponding at least to the portion where a heating section is formed, thereby achieving uniform heating-cooling characteristic and heat transmission efficiency at the heating section of a thermal head over the entire row of heating elements.

CONSTITUTION: Crown of a partially glazed portion 9 is polished and the portion where a heating section is formed is flattened to be in parallel with an insulating substrate 1. Alternately, the polished face of a partially glazed portion 12 is inclined toward the feeding side of thermographic paper 14. By such arrangement, pressure contact state with the thermographic paper or an ink sheet is uniformed and the height of the partially glazed portion is uniformed to h2. Consequently, fluctuation of thermal characteristic at the heating section, which causes uneven print density, can be suppressed. Furthermore, since the heating section contacts with the thermographic paper 14 around a point where the pressure contact force is highest, heat transmission efficiency can be further improved.