Abstract: An apparatus for punching transversely throughgoing coaxial holes in spaced walls of a workpiece has a holder supporting the workpiece and an outer tool part formed with a pair of transverse bores and displaceable between an advanced position engaged over the workpiece on the holder and outwardly flanking the walls and a retracted position spaced from the holder. An inner tool part formed with a transversely throughgoing bore is displaceable in the advanced position of the outer tool part between an advanced position engaged between the walls and with its bore coaxial with the bores of the outer tool part and a retracted position with its bore spaced from the workpiece in the holder. The outer tool part is formed with a waste passage aligned with the inner-part bore in the retracted position of the inner part.