each of the painted out elements 30 30 and straight line elements 31 31 the pattern data stored in the pattern data memory 2 include the data for controlling the operation of thread tension adjusting device 26 in addition to the data for controlling the operation of the work feeding mechanism 25 and of the stitch amplitude adjusting mechanism 24 the pattern data may be modified regarding a plurality of predetermined elements to be stitched in a composite stitch pattern 0026 fig4 shows the examples of patterns formed by the pattern data as modified in fig4 a shows a stitch pattern formed by use of the data before the same is modified b shows the same stitch pattern but having the straight stitch lines 31 u2032 31 u2032 elongated as compared with the straight stitch lines 31 31 of a d shows the same stitch pattern but having further elongated straight stitch lines 31 u2033 31 u2033 as compared with the straight stitch lines 31 u2032 31 u2032 of b further d shows the stitch pattern modified to have the straight stitch lines 31 increased up to four 0028 fig5 shows the thread tension set to each of the pattern elements of the composite pattern as to the zigzag stitch portions that is the painted out portions 30 in fig2 the thread tension adjusting device 26 is adjusted to give.