A curvature examining jig for examining the curvature of a circuit board quickly and accurately includes a platform and a carrier. An examining region is defined on the platform so as for the circuit board to be disposed flatly within the examining region. A recess is disposed in the examining region and configured to receive a protrusion of the circuit board. The carrier is slidably coupled to the platform, configured to move along the margin of the circuit board, and provided with a plurality of plug gauges facing the platform closely and configured to move to the examining region along with the carrier. Accordingly, the curvature examining jig is convenient in holding a circuit board having a protrusion, quick and accurate in examining the curvature of the circuit board, and effective in enhancing the efficiency of production lines.