Abstract: In a thread supply device used in a sewing apparatus having a plurality of needles and a looper mechanism, needle threads guided to the needles and a looper thread guided to the looper are cut by a thread cutting unit at a cutting position, which is off a thread supply path, after a sewing operation is finished but before the following sewing operation starts. The thread supply device comprises a supply mechanism, a stopping mechanism, a memory and a control unit. The supply mechanism forcibly supplies the needle threads and the looper thread. The stopping mechanism stops the threads from being supplied. The memory stores an extra length of each thread, which is required for a cutting operation. The control unit reads out the extra length from the memory and controls the supply mechanism and the stopping mechanism so that each thread is supplied in the extra length.