PURPOSE: To perform automatic production of reverse sewing data through one action of a key by providing a function to automatically convert thread cut data present in the middle of seam data and start data.

CONSTITUTION: When reverse data is produced, seam data in a forward direction already stored in a memory means is orderly read in a reverse direction by means of a read means 30, and end data is read, it is converted into middle stop data. The data is analyzed by an analyzing means 31, and when analyzed result data is start data, it is converted to thread cut data, and when it is thread cut data, the thread cut data is converted to start data. When it is seam data, i.e., needle position data, the code is inverted, and when it is empty data, end data is generated. This constitution automatically produces sewing data in a reverse direction to inputted seam pattern data (from P1 to P9), i.e., top data of P20, P21,..., P36, P37.