A looper is brought into an advance state at the end of sewing, and a looper thread hanging hook arranged on the right rear side of a needle drop position is forced to advance and retreat to catch a looper thread running to the rear side of the looper and hold it on the rear side of the needle drop position. After performing sewing for one stitch in this state, the thread cutting hook arranged on the right side of the needle drop position is forced to advance and retreat to catch the looper thread running to the rear side of the looper with a first hold section and catch needle threads and the looper thread held by the looper thread hanging hook with a second hook section, and then these threads are collectively cut by bringing them into slide-contact with a thread cutting knife.
