A hemming unit may include a hemming tool, an actuator for moving the hemming tool, and a link mechanism connecting the actuator and the hemming tool. Therefore, the hemming tool can be moved by the actuator by means of the link mechanism to perform a hemming operation. A hemming apparatus may include at least one hemming unit, a workpiece support for supporting a workpiece during the hemming operation, and a workpiece holder for holding the workpiece in position relative to the workpiece support during the hemming operation.