Patent ID: 8850691

Claim:
A manufacturing method for a heating resistor element, comprising: a concave portion forming step of forming a concave portion on at least one of bonded surfaces between an insulating substrate and a heat accumulating layer; a bonding step of causing the bonded surfaces between the insulating substrate and the heat accumulating layer to adhere to each other to bond the insulating substrate and the heat accumulating layer; and a resistor forming step of forming a heating resistor at a position on the heat accumulating layer, the position being opposed to the concave portion, wherein the concave portion forming step comprises: blocking the concave portion by a portion of the heat accumulating layer, a portion of the insulating substrate, or both, wherein the portion of the heat accumulating layer and the portion of the insulating substrate do not form the bonded surfaces; and processing an inner surface of the concave portion on a side of the heat accumulating layer to be formed smoothly and processing an inner surface of the concave portion on a side of the insulating substrate to have surface roughness Ra of 0.2 μm or more.