To enhance the linearity of protrusion parts of a glaze layer of the heater element plate used in a thermal print head.

The manufacturing method of the thermal print head includes the steps of arranging and fusion bonding a plurality of patterns of glaze layers 25 including the protrusion parts 21 extending in a line shape formed of a second insulation material with different thermal expansion coefficient from a first insulation material along the long sides of rectangular head base plates 22 formed by dividing a raw plate 71 on the surface of the raw plate 71 formed of a first insulation material, and dividing the raw plate 71 along with the graze layer 25 to form head base plates 22, and further includes a glaze layer forming step forming the lines of the protrusion parts 21 in a convex arc shape facing toward the long sides of the head base plates 22 and a dividing step dividing the raw plate 71 along with the glaze layer 25 along the long side of the head base plates 22 after the glaze layer forming step.