The introduction of active-tension enables the separate setting of suitable thread tensions for sewing sleeves on a portion-by-portion basis. This prevents an inadequate thread tension at a portion where the shirring amount is large or an excessive thread tension at a portion where the shirring amount is small. In addition, specified tension settings can be stored in the memory on a pattern-by-pattern basis and can be reproduced with ease.

The operation mode of a single machine can be changed over between manual, semi-auto and full-auto according to the ease of use for each operator.

The machine prevents an abrupt change in the shirring amount at the sewing-step changing point by utilizing a smoothing function. This upgrades the finished quality of the seams.

In addition, the machine comes provided with various data inputting features, such as teaching, grading and mirroring for the easy programming of sewing data and for improved operating efficiency.