To make it possible to dispose the sample of any shape on a thermobalance under the same conditions and to calibrate the temperature under the same conditions even in the actual measuring atmosphere.

A standard sample 3 is introduced into a vessel 2 having heat resistance like glass without exposing the sample 3 directly with any atmosphere such as pure oxygen atmosphere or steam atmosphere, the vessel 2 is fully filled with inert gas, and the sample 3 and the gas are sealed. This temperature calibrating sample 1 for a thermal analyzer is installed at one of the balance, heated, and weight change is detected. In this case, even if it is exposed with various gases and heated, no chemical reaction or no phase transition occurs, the standard sample is heated under the same conditions to make it possible to calibrate the temperature.