To provide an accurate method of determining stress of a thin film in depositing the thin film on a substrate, and sequentially identifying the stress applied to a line structure.

The curvature of the substrate before depositing the thin film is measured, the curvature after depositing the thin film is measured, the stress is computed from measured curvature information, based on simple analytical functions, and comparison before and after adhesion of the thin film is performed, thereby removing error in measuring the curvature. The curvature information can be optically obtained by a coherent gradient sensing method capable of full-field measuring of an illuminated area, for example.