Disclosed is a birefringence measuring apparatus and method for measuring birefringence of a sample in a reduced time and in a simple manner. The birefringence measuring apparatus includes a light projecting unit for projecting approximately circularly polarized light upon a sample, a Stokes meter for detecting a state of polarization of light from the sample, and a calculating system for calculating birefringence of the sample on the basis of a Stokes parameter from the Stokes meter.