a shows one unit of sewing data of a stitch that is the first byte stores the above described control instruction the second byte stores stitch data or the amount of x axis feed of the idle feed data and the third byte stores stitch data or the amount of y axis feed of the idle feed data the one unit of sewing data as shown in fig7 b are stored in predetermined addresses in the inputting order beginning from the first stitch to the end data which is one of the control instructions of sewing data fig8 is a flow chart for a description of the operation of the sewing data forming device according to the invention when the menu key 34 curve input 34 is selected with the switch 12b of the mouse 12 a sewing data forming mode by curve inputting is established in step s10 of fig8 in step s11 coordinate data points a a 5 a 10 a 15 a 40 and j inputted are read and stored in the ram 24 shown in fig3 successively when the menu key 34 curve input 34 is operated again in step s12 step s13 is effected in step s13 inclination data g g 5 g 10 g 15 g 40 and gj are applied to the coordinate data of the points a a 5 a 10 a 15 a.