A heating device includes a substantially cylindrical shaft joined to a joint surface of a plate-shaped ceramic substrate opposite to a heating surface, the ceramic substrate including a resistance heating element embedded in the ceramic substrate. The shaft includes a flange portion formed in the end joined to the ceramic substrate and a first cylindrical portion connecting to the flange portion, and a ratio D3/D1 of an inner diameter D3 of a joint area in the flange portion and an outer diameter D1 of the first cylindrical portion is not less than 92%.