The burnishing part includes: a mandrel; burnishing rollers; a frame; an adjustment member that presses the frame axially from one end thereof to adjust the axial position of the frame with respect to the mandrel; and an elastic member that is arranged axially on the other side of the frame to support the frame. The reaming part includes: a base part that is detachably attached to the mandrel; and machining blades that are formed integrally with the base part. This results in providing a combined machining tool that is capable of machining an inner peripheral surface of a workpiece having a smaller diameter, and a machining method using the same.