Abstract: A jig has a main body. The main body is provided with a rotatable engaging shaft. The engaging shaft is provided with a main body fixing portion actuator and a workpiece clamping portion actuator. The main body fixing portion actuator is provided with a main body fixing portion drivable by the main body fixing portion actuator. The workpiece clamping portion actuator is provided with a workpiece clamping portion drivable forward and backward by the workpiece clamping portion actuator. When the engaging shaft is rotated, attachment and detachment of the main body and clamping of a workpiece can be performed.