Abstract: In a vibration-resistant interferometer, an interference fringe image obtained by an image capturing means is analyzed and an optical path difference between a reference light component and an object light component is maintained at a predetermined value with reference to the result of this analysis, thereby making its optical system simple in structure, easy to adjust, and inexpensive to manufacture and maintain. A Fizeau-type interferometer, a CCD camera for viewing an interference fringe, a computer for analyzing the interference fringe image information obtained by the CCD camera to calculate the shape of the sample surface or the amount of vibration or inclination of the sample surface, and a PZT driving circuit for transmitting predetermined driving signals to PZTs are provided.