Various embodiments provide a substrate processing apparatus for grinding a substrate, and a display device including a substrate in which a hole is formed in an edge of the substrate using the substrate processing apparatus. The substrate processing apparatus for processing a display substrate includes a body which, in operation, rotates, a cylindrical grinding part connected to the body, and a lateral groove formed in a surface of the cylindrical grinding part. The lateral groove is configured to accommodate the display substrate. Thus, it is possible to form a hole by grinding an edge of the display substrate so as to be matched with a designed value.