A three-dimensional image acquisition apparatus for acquiring a plurality of images of an object with the positions in focus shifted at predetermined step distances used for measuring the three-dimensional shape of an object. This three-dimensional image acquisition apparatus comprises an image forming lens, a two-dimensional image pickup means for converting the optical image of an object into electric signals and outputting the electric signals, at least one rotary support which has a plurality of transparent plates differing in thickness or refractive index or both secured thereto and is disposed so that when it is rotated the transparent plates in turn intersects the optical axis between the image forming lens and the object or the image forming lens and the two-dimensional image pickup means, and at least one drive means for intermittently or continuously rotating the rotary support. By this three-dimensional image acquisition apparatus, the image can be acquired in considerably less time with a higher positional accuracy.