A complex tool has a main body and a turning tool provided at an outer periphery portion of the main body. The turning tool is capable of machining on a rotating workpiece without rotating itself. An insert installed on the turning tool has a top end which contacts a workpiece by projecting a predetermined amount outside the main body's outer peripheral face. It also projects a predetermined amount from a top end portion of the main body in a direction of an axial center of the tool. The complex tool also has a rotating tool for machining by rotating itself. The rotating tool accomplishes machining corresponding to an axial center of the main body.