Abstract: There is provided a curvature measuring apparatus and method using multiple beams. m×n multiple beams generated by an m×n laser diode (LD) array or an m×n vertical cavity surface emitting laser array having a uniform pitch are converted into multiple divergent or multiple parallel beams. The multiple beams strike and reflect from the surface of a thin film formed on a substrate Then, the multiple beams are detected by an m×n spot array in a detector such as a charge coupled device (CCD) or a CMOS image sensor. The spot spacing between the beams in the array is measured in a direction parallel to the incident plane. The spot spacing between the beams is changed by the curvature of the substrate in the direction parallel to the incident plane and the curvature may be expressed by a function including change in beam spacing, an incident angle, a distance between the surface of the thin film and the detector.