To enable the strenuous control of the dispersion of the quantity of the remaining thread after cutting at the time of the completion of the eyelet hole overcasting even when the seam length of an eyelet hole sewing varies.

When an air cylinder for cutting the thread 24 is driven at the time of the completion of the sewing, an upper blade member 21 and a lower blade member 22 are turned in reverse directions by the turning of a first actuation link 30 and a drive link 35, and a situation that a drive shaft 34 of a second actuation link 39 and a third pin 41 and a fourth pin 42 of a second connection link 40 are located on one straight line continues for a prescribed period while the lower blade 22 is turned. At this time, although the second actuation link 39 is turned, only the upper blade 21 is continuously turned in a clockwise direction in the situation that the turning of the lower blade 22 is substantially stopped. Thereby, the bobbin thread and the core thread are cut by only the turning of the upper blade 21 in the situation that the turning of the lower blade 22 is substantially stopped.