We aim at industrial standardization of a testing method for thermal expansion behavior of thermal barrier coatings (TBCs). A push-rod type thermomechanical analysis (TMA) was selected as a widely used method, and was examined whether to evaluate accurate thermal expansion behavior from a thin specimen with the thickness of practical TBCs. We first demonstrated that the TMA measurements with a specimen support and optimum conditions were able to provide accurate mean coefficients of thermal expansion (CTEs) of dense yettria- stabilized zirconia (YSZ) from the thin specimens with the thickness down to 0.3mm. In addition, it showed good reproducibility with small measurement error less than 5%. This modified TMA was also assured to be able to accurately evaluate CTEs and sintering behavior of plasma-sprayed YSZ from 0.3mm-thick specimens. Therefore, we actually used this method to explore the influence of annealing on thermal expansion behavior of the YSZ coating. As a result, the modified TMA measurements detected a slightly monotonie decrease in CTE with annealing.