According to one embodiment, a three-dimensional shape measuring apparatus includes at least an aperture plate that is provided with a plurality of confocal apertures which are two-dimensionally arranged to have a predetermined arrangement period, and an aperture plate displacement portion that displaces the aperture plate at a constant speed in a predetermined direction perpendicular to the optical axis direction. Further, the aperture plate is provided with a cover member which is moved integrally with the aperture plate and which includes a transparent body allowing the light beams from the light source to pass therethrough and to be irradiated to the plurality of confocal apertures, and protects the plurality of confocal apertures from dust. Further, an imaging optical system, by which each of reflected light beams is guided to a photo-detector, is designed in consideration of optical properties of the whole optical system including the transparent body of the cover member.