a looper having an extended portion, wherein a thread hole is formed on a tip portion of the extended portion, and a looper groove is formed along the extended portion;

a looper shaft holding the looper such that the looper is swivelable between a front position and a rear position in synchronization with a vertical motion of a needle and interlockingly with a motor;

a thread pipe fixed to the looper shaft, wherein a thread inserting port at one end of the thread pipe and a thread discharging port at the other end of the thread pipe is communicated such that a thread can be inserted therethrough;

air supplying means for supplying air toward the thread inserting port when a nozzle is disposed at a spraying position opposed to the thread inserting port of the thread pipe;

switching means for disconnecting the looper from the looper shaft when the looper is at the front position; and

moving means for moving the looper, which is disconnected from the looper shaft by the switching means, to the rear position,

wherein, when the looper is disconnected from the looper shaft and is moved to the rear position, the thread discharging port of the thread pipe becomes coincident with the thread hole of the looper, and the thread inserting port of the thread pipe becomes coincident with a tip of the nozzle disposed at the spraying position.