This paper describes a new simultaneous phase stepping method for moire interferometry. Conventional phase-stepping methods are widely accepted but the measured data are vulnerable to disturbances such as air fluctuations, temperature changes, vibrations and so on during the interferogram recording. To overcome this, a unique camera having a micro-retarder array on a CCD is used for observing interferograms. The specific structure makes it possible to calculate polarization states. Using this camera in a moire interferometer, the distribution of in-plane displacements is obtainable from a single image.