PURPOSE: To prevent a moving cutter from missing in capturing a sewing thread with a simple mechanism control by driving the moving thread cutter by an exclusive motor and stopping a shuttle at the optimum rotation position other than the normal stopping position at the time of cutting the thread.

CONSTITUTION: A loop of an upper thread 35 is formed by the friction between the vertical movement of a sewing thread 5 at a needle settling point and the processed cloth. The loop is captured by cutter point 21A of a shuttle/hook 21. In this case, an upper thread 35A from the processed cloth passes over an inner shuttle 22 and intertwined with a lower thread 36 from a bobbin 23 in the inner shuttle 22. Then, in the case of cutting the thread, the shuttle/hook 21 is rotated from the normal stopping position and, after the cutter point 21A captures the loop of the upper thread 35, a moving cutter 14 is moved by operating a thread cutting motor during the upper thread 35 passes through the shuttle/hook. Then, after the moving cutter 14 is slipped into between the upper thread 35 and the lower thread 36 from the processed cloth and the upper thread B from the sewing thread 5, the sewing threads 35A and 36 are cut by a fixed cutter 20 and the moving cutter 14 by retreating the moving cutter 14.