PURPOSE: To perform both radius chamfering and inner surface finishing operations at a time and make these operations into efficiency, by holding a printing wire guide member between a pair of abrasive grain fluidizer supplying members in that state that an abrasive grain fluidizer supply opening is matched with a printing wire guide port.

CONSTITUTION: In the state that an abrasive grain fluidizer supply opening 4 is matched with a printing wire guide port 2 by a locating pin 9, the wire guide member 1 plurally held by a carrier 8 is held between a pair of abrasive grain fluidizer supplying members 3a and 3b and clamped to a jig 10. And, temperature of an abrasive grain fluidizer 5 is controlled by a temperature sensor 6 and a temperature regulator 7 and, while keeping the specified fluidity, the abrasive grain fluidizer 5 is made to reciprocatively flow in the printing wire guide port 2 by a supply source 11, whereby both radius chamfering for a square part and inner surface finishing operations are performed at the same time. Thus, improvement in machining efficiency and stabilization in machining quality are well promotable.