PURPOSE:To obtain a large speed difference with extremely simple constitution when a carriage speed is changed, by using a differential gear device. CONSTITUTION:During the constant-speed feed of an arm device 26, a worm gear 69 rotates through the rotation of the rotary shaft 51 of a turntable and its turning force is reduced by a differential gear device 70 and transmitted to a pulley 66. This pulley 66 rotates a belt 64, and an electromagnetic clutch 63 is turned on to feed the arm device 62 at a very slow and constant speed. In a fast feed state, the turning force of a fast feed motor 75 is transmitted to the belt 64 via worm gear 73, the device 70 and the pulley 66. Therefore, with the clutch 63 turned on, the arm device 26 is fast forwarded. Consequently, when the carriage speed is changed, a large difference in speed is obtained and only one belt and electromagnetic clutch each are required, so the constitution of a carrying means for the arm device is simplified extremely.