Abstract: A three-dimensional shape measuring apparatus includes a projection device having a projecting plane witha grating pattern formed therein and a light source for illuminating, through the projection plane, an object of interest located at an arbitrary position in the same three-dimensional coordinate system as that of the projection device, an observation device located in the same three-dimensional coordinate sysem as that of the object and having an observation plane and a specific point located between the observation plane and the object. In the apparatus, the grating pattern in the projection plane is projected on a surface of the object to form a projected grating pattern thereon when the light source is turned on, the grating pattern projected on the object is observed in the observation plane.