Substrate processing apparatus and method for detecting abnormality of substrate

A substrate processing apparatus having a detecting unit that can detect an abnormality of a substrate such as a crack of the substrate or chipping of the substrate is disclosed. The substrate processing apparatus includes a polishing unit 3A-3D configured to polish a substrate, a cleaning unit 73, 74 configured to clean the polished substrate, a substrate abnormality detection unit 40 configured to detect an abnormality of the substrate, and a substrate transporting mechanism 6, 12, 77 configured to transport the substrate in the order of the polishing unit 3A-3D, the substrate abnormality detection unit 40, and the cleaning unit 73, 74. The substrate abnormality detection unit 40 includes an imaging device 42 configured to image the substrate, and an output monitoring unit 45 configured to determine a status of the substrate by comparing a signal obtained from the imaging device 42 with a predetermined threshold.