A method for preventing seam ravel of multi-thread chain stitches is provided. After normal sewing is terminated with a looper set in a forward movement state, a state in which a needle thread loop caught by the looper is subjected to position-holding at a position closer to a forward movement end of the looper than a descent position of a needle is maintained until the needle descends through the needle thread loop caught by the looper. Thereafter, the position-holding of the needle thread loop is released to permit a sewing action for at least one stitch, thereby allowing the needle thread loop to be self-looped with a needle thread held by the needle. This surely strongly prevents the seam ravel of multi-thread chain stitches formed by the single needle, irrespective of the dimension of tension applied to the needle thread and the looper thread.

A sewing machine includes a threading mechanism, a holding member, and a movement mechanism. The threading mechanism is configured to move a hook between a standby position and an operative position. The holding member includes a cutting blade and a clamping portion. The cutting blade is configured to cut an upper thread. The clamping portion is configured to clamp and hold a thread end of the cut upper thread. The movement mechanism is configured to move the holding member to a first position and a second position. The first direction is a direction from the standby position to the operative position. The second position is a position on a second direction side with respect to the first position. The second direction is a direction opposite to the first direction.

A sewing machine includes a threading mechanism, a holding member, and a movement mechanism. The threading mechanism is configured to move a hook between a standby position and an operative position. The holding member includes a cutting blade and a clamping portion. The cutting blade is configured to cut an upper thread. The clamping portion is configured to clamp and hold a thread end of the cut upper thread. The movement mechanism is configured to move the holding member to a first position and a second position. The first direction is a direction from the standby position to the operative position. The second position is a position on a second direction side with respect to the first position. The second direction is a direction opposite to the first direction.

A sewing machine includes a needle bar, a needle bar release mechanism, a drive portion, a contact member, and a switching mechanism. The needle bar is configured to move up and down. The needle bar release mechanism is configured to connect and disconnect the transmission of the driving force between the drive shaft and the needle bar. The drive portion is configured to drive the needle bar release mechanism. The contact member is configured to come into contact with the needle bar in a case where the needle bar is positioned at a top dead point of the range within which the needle bar is able to move up and down. The switching mechanism is configured to switch the position of the contact member between a first position and a second position.

A sewing machine includes a needle bar, a needle bar release mechanism, a drive portion, a contact member, and a switching mechanism. The needle bar is configured to move up and down. The needle bar release mechanism is configured to connect and disconnect the transmission of the driving force between the drive shaft and the needle bar. The drive portion is configured to drive the needle bar release mechanism. The contact member is configured to come into contact with the needle bar in a case where the needle bar is positioned at a top dead point of the range within which the needle bar is able to move up and down. The switching mechanism is configured to switch the position of the contact member between a first position and a second position.