Abstract: A heater substrate has an insulating substrate having a first surface and a second surface on the opposite side relative to the first surface and at least one heating element of spiral shape including plural heater wire pieces and positioned in or on the insulating substrate. The heating element of spiral shape has at least one adjustment section including a turn of all or some of the plural heater wire pieces. The plural heater wire pieces include a first heater wire piece and a second heater wire piece adjacent to the inner side of the first heater wire piece. In the adjustment section, the length of the first heater wire piece is smaller than the length of the second heater wire piece.

Abstract: A circuit board has: an insulating substrate formed by plural ceramic insulating layers being layered on one another and having a first surface and a second surface on the opposite side to the first surface; a circuit conductor passing through the inside of the insulating substrate and positioned in a region from the first surface to the second surface; and at least one heating wire positioned in the insulating substrate. The heating wire is positioned in, among plural interlayer regions between the ceramic insulating layers, at least one interlayer region between the ceramic insulating layers and has a mesh shape having plural first through holes through which a portion of the circuit conductor passes and having plural second through holes through which the circuit conductor does not pass.