Pressurized gas for carrying looper thread by gas is generated by gas supply pump operated by changing over a sewing-machine motor, which drives stitch forming device, looper threading is performed through loopers by one-touch operation. Gas carrying threading device of sewing machine, comprising: looper thread introduction mechanism inserts looper thread guided to loopers; hollow looper thread guide extends from looper thread introduction mechanism to looper thread inlets and has looper thread guide outlets; gas supply pump for performing looper threading by carrying looper thread by gas from looper thread introduction area through hollow looper thread guide to looper thread loop-taker point outlets; clutch for transmitting power from sewing machine motor M to drive shaft which drives stitch forming device including loopers at time of stitch formation or to gas supply pump at time of looper threading.