BORING BAR AND BORING APPARATUS HAVING BORING BAR

PROBLEM TO BE SOLVED: To adjust each diameter of knife edges of one or a plurality of cutters arranged in the circumferential direction with a simple structure. SOLUTION: A boring bar 20 is adjustable in its knife edge diameter and a boring apparatus uses the boring bar. The boring apparatus is provided with a body shaft 22 of the boring bar 20 and an adjusting shaft 50 inserted therein. A plurality of cutter fitting pats 24A, 24B are arranged in the circumferential direction on the body shaft 22, and a plurality of cam faces corresponding thereto are formed on the outer peripheral surface of the adjusting shaft 50 inserted in the body shaft 22. The cutter fitting parts 24A, 24B have cutter holding members 26A, 26B moving in the radial direction of the body shaft with cutters 28A, 28B held thereon, and a drive pin 29 is projected on a cam face side. An elastic pressing part 30 is provided in a position adjacent in the axial direction of the body shaft relative to the cutter holding members 26A, 26B, thereby elastically pressing the respective cutter holding members 26A, 26B inward in the radial direction to keep the contact state of the drive pin 29 and the cam face.