A combined machining tool comprising: a shank that has its rear end to be mounted on a processing machine; a burnishing part that is arranged on the shank and burnishes an inner peripheral surface of a workpiece; and a reaming part that is arranged in front of the burnishing part and executes reaming wherein the burnishing part comprises: a mandrel that is fixed to the shank and has an outer peripheral surface na tapered shape; rollers that are arranged on the outer peripheral surface of the mandrel; a frame that holds the rollers so as to be rollable on the outer peripheral surface of the mandrel; an adjustment member that presses the frame axially from one end thereof to adjust its axial position with respect to the mandrel; and an elastic member that is arranged axially on the other side of the frame to support the frame, and characterised in that the reaming part comprises: a base part that is detachably attached to the mandrel; and a machining blade that is formed integrally with the base part, wherein a hole part is formed in the mandrel to have inside a tapered surface whose diameter decreases rearward, and a cylindrical part s formed in the base part so as to be fitted into the hole part, to have outside a tapered surface whose diameter decreases rearward, so that the diameter of the tapered surface of the hole part is smaller than that of the tapered surface of the cylindrical part , at an axial position where a stepped end face of the reaming part is aligned with the front end surface of the mandrel . a shank that has its rear end to be mounted on a processing machine; a burnishing part that is arranged on the shank and burnishes an inner peripheral surface of a workpiece; and a reaming part that is arranged in front of the burnishing part and executes reaming wherein the burnishing part comprises: a mandrel that is fixed to the shank and has an outer peripheral surface na tapered shape; rollers that are arranged on the outer peripheral surface of the mandrel; a frame that holds the rollers so as to be rollable on the outer peripheral surface of the mandrel; an adjustment member that presses the frame axially from one end thereof to adjust its axial position with respect to the mandrel; and an elastic member that is arranged axially on the other side of the frame to support the frame, and a mandrel that is fixed to the shank and has an outer peripheral surface na tapered shape; rollers that are arranged on the outer peripheral surface of the mandrel; a frame that holds the rollers so as to be rollable on the outer peripheral surface of the mandrel; an adjustment member that presses the frame axially from one end thereof to adjust its axial position with respect to the mandrel; and an elastic member that is arranged axially on the other side of the frame to support the frame, and characterised in that the reaming part comprises: a base part that is detachably attached to the mandrel; and a machining blade that is formed integrally with the base part, a base part that is detachably attached to the mandrel; and a machining blade that is formed integrally with the base part, wherein a hole part is formed in the mandrel to have inside a tapered surface whose diameter decreases rearward, and a cylindrical part s formed in the base part so as to be fitted into the hole part, to have outside a tapered surface whose diameter decreases rearward, so that the diameter of the tapered surface of the hole part is smaller than that of the tapered surface of the cylindrical part , at an axial position where a stepped end face of the reaming part is aligned with the front end surface of the mandrel . <EOS>