Patent ID: 7432474

Claim:
A heating device, comprising: a plate-shaped ceramic substrate including a heating surface on which an object to be heated is placed; a resistance heating element disposed in the ceramic substrate; and a substantially cylindrical shaft an end of which is joined to a joint surface of the ceramic substrate opposite to the heating surface, the shaft supporting the ceramic substrate, wherein the shaft includes a flange portion formed in the end joined to the ceramic substrate, a first cylindrical portion connecting to the flange portion, the flange portion extending beyond an outer diameter D 1 of the first cylindrical portion, and a second cylindrical portion connecting to the first cylindrical portion on a side further from the ceramic substrate, the outer diameter D 1 of the first cylindrical portion being larger than an outer diameter D 2 of the second cylindrical portion, and a ratio D 3 /D 1 of an inner diameter D 3 of a joint area in the flange portion and the outer diameter D 1 of the first cylindrical portion is not less than 92%, to provide a high strength airtight joint at least along an inner peripheral portion of a joint interface of the flange portion and the joint surface of the ceramic substrate.