PURPOSE: To heighten the working speed and to reduce the working cost remarkably, by connecting an ultrasonic wave oscillator to a holder having a grooved tool and performing grooving at the inside of a heat exchange pipe by pressing the same.

CONSTITUTION: A heat exchange pipe 11 is held by pipe clamps 12, 13 and clamped by external threads 14, and a grooving tool 15 is faced on the center of openig 11a of the pipe 11. Vibration from an ultrasonic oscillator 18 is transmitted to the grooving tool 15 through a holder 17, and at the same time, the grooving tool 15 is pressed by a pressure driving device 19 through the holder 17. Accordingly, the grooving tool 15 cuts the inside of the heat exchange pipe 11 while vibrating. Therefore, the pitch of the groove can be made as small as 0.2mm, and working can be made with small cutting resistance.