An apparatus and method for measuring a three-dimensional shape of an object using a projection moiré device. The method comprises the steps of obtaining a grid pattern image projected on a reference plane of a moving table and applying a buckets algorithm thereto, thereby achieving a reference phase, obtaining a grid pattern image projected on the object set on the moving table and applying a buckets algorithm thereto, thereby achieving an object phase, calculating a difference phase between the object phase and the reference phase, thereby achieving a moiré phase, and unwrapping the moiré phase, thereby achieving a level information of the object. The apparatus and method measure the three-dimensional shape using a projection grid without a reference grid, thereby achieving compactness of equipment, simplicity in usage and manufacturing cost reduction.