To supply a bobbin thread dedicated thread for a bobbin without detaching the bobbin by providing a bobbin driving member rotating the bobbin only at the time of thread winding operation, a thread holding member holding the neighborhood of the tip of the bobbin thread dedicated thread to enter over an rotating hook bobbin case holder and a putting out means moving the thread holding member.

A cup-like rotating hook bobbin case holder 18 is arranged within a rotating hook 7 rotated linked with a lower shaft at a horizontal shuttle 4 arranged in front of a needle 3 reciprocated in a vertical direction linked with an upper shaft at the time of sewing operation and a bobbin 22 forming flanges at its upper/lower parts is housed within this holder 18. Then, the bobbin 22 is rotate-driven by a bobbin driving member only at the time of thread winding operation and the neighborhood of the tip of the bobbin thread dedicated thread supplied at this time is normally held by a thread holding member 48 whose tip part is saved to the neighborhood of the outer peripheral surface of the hook 7 to allow the tip part to enter over the holder 18 at the time of thread winding operation. Then this member 48 is moved to a thread hooking position by the putting-out means 261 and thread winding is started.