the 0 1 sec timer the rotation speed of the electric motor 15 comes down from 200 r p m to 100 r p m the set speed as the discrimination in the discrimination process p15 keeps no until the timer terminates the program is advanced to a discrimination process p33 for discriminating again whether the ls memory is set or not the then coming out no discrimination advances the program just like in the case of the discrimination process p31 to a stitch pattern forming process p34 other than the non ravel stitching in order to further continue the formation of the selected stitch pattern yes discrimination in the discrimination process p15 due to the termination of the timer moves the program to the discrimination process p16 which makes yes discrimination because of the np memory being set in the above mentioned step p7 to advance the program to the discrimination process p23 no discrimination continues until the needle position signal falls in this process p23 so the program advances to a discrimination process p35 for discriminating again whether the ls memory is set or not no discrimination in this process p35 advances the program to a stitch pattern forming process p36 other than the non ravel stitching.