Abstract: A strain inspection apparatus is provided that includes a drive mechanism for rotating a polarizing plate corresponding to an analyzer and that can perform a test without the polarizing plate being manually rotated by an operator. A strain inspection apparatus includes a camera, a second polarizing plate, a quarter wavelength plate, a first polarizing plate, a diffusion plate, a light source and a drive mechanism for stepwise rotating the second polarizing plate at an arbitrary angle. The camera, the second polarizing plate, the quarter wavelength plate, the first polarizing plate, the diffusion plate and the light source are aligned on the same axis (test axis), and the drive mechanism automatically rotates the second polarizing plate corresponding to an analyzer so as to measure a retardation and an optical axis direction.