To provide a heating tester capable of closing an air chamber formed by a tester body and a base tube by a wall face of a small-size heat sensor, properly maintaining a distance between a heat sensing part and a heat generation part, and preventing a scorch of a ceiling face or heating deformation of the small-size heat sensor caused by overheating.

In this heating tester with the cross-sectionally nearly trapezoidal base tube, an adapter allowing lead-in of the heat sensing part of the heat sensor, formed with an opening part smaller than a case of the heat sensor can be installed on the upper face of the base tube.