A workpiece mounting system which is highly versatile and can reduce a cycle time. A workpiece mounting system (1) mounts a sunroof member (3) to an inner panel (2A) of a body (2). The workpiece mounting system (1) is provided with a first robot (5), a second robot (6), and a control device (7) for controlling the first and second robots. The control device (7) performs a step of calculating as positional information the position of the sunroof member (3) and the position of the inner panel (2A) by means of a CCD camera of the first robot (5), a step of holding and conveying the sunroof member (3) by means of the first robot (5) on the basis of the positional information and positioning the sunroof member (3) relative to the inner panel (2A), a step of temporarily fixing the sunroof member (3) to the inner panel (2A) by means of the first robot (5), and a step of finally fixing the sunroof member (3) to the inner panel (2A) by means of the second robot (6) on the basis of the already calculated positional information.