An apparatus and a method for supplying thread in a chain stitch sewing machine are disclosed, the apparatus comprising a needle vertically reciprocating between a top end point and a bottom end point in one sewing cycle; a looper horizontally reciprocating in one sewing cycle; a thread supply device for forcibly supplying a needle thread to the needle; and a thread supply control device for controlling the thread supply device so that the needle thread is supplied in at least two periods in each sewing cycle, the periods being discontinuous.