To improve a yield while suppressing the lack of a glass layer.

A thermal print head for performing printing on a medium moved in a sub-scan direction includes a ceramic substrate 22, a heat insulation layer 25 formed of glass, a heating resistor 26, and an electrode provided at a metallic wiring layer 28 connected to both ends of the heating resistor 26. The heat insulation layer 25 has a projected line 21. The projected line 21 has an edge side slope 72 at the side of the edge 91 of the ceramic substrate 22 and a central side slope 73 opposite to the edge side slope with a ridge line 70 interposed between both the slopes. The edge side slope 72 is formed in a convex shape. The central side slope 73 has a first slope part 74 connected to the ridge line 70 and a second slope part connected to a flat part. The first slope part 74 is formed in a convex shape and the second slope part 75 is formed in a concave shape. The heating resistor 26 is formed at the edge side slope 72 of the projected line 21.