A workpiece conveying system is provided, which includes a workpiece including a workpiece main body, a cylindrical gripping part protruding from the workpiece main body, and an engaging plate attached to a tip-end surface of the gripping part, a chuck device including three jaws configured to grip the gripping part in radial directions of the gripping part, and a robot to which the chuck device is attached. The engaging plate includes an overhang part protruding from the gripping part along the tip-end surface of the gripping part, and an engaging slot, into which one of the three jaws fits, is formed in the overhang part.