To provide a throat plate which can prevent a lower string 8 from going up unusually over a upper cloth when a satin stitch having a extremely small side-swinging width j value is embroidered, and which allows to change the shape of the of the needle board arbitrarily even if the tension of a string is varied with changes of characteristics of cloths and strings.

An embroidering sewing machine has a bed, a needle and a shuttle. Embroidering is carried out on a cloth surface on a throat plate by operating the needle and the shuttle interlockingly. On a mast upper surface of the throat plate, there is an additional member to the throat place which member has a through hole whose diameter is double of the swinging width of an approximate satin stitch and whose center is a dropping hole of the needle. At the upper part of the additional member, a through hole having a further larger diameter is bored.