PURPOSE: To perform alignment of a presser bush agreeably by providing a magnetic body attracted corresponding to polarity of a plurality of magnetic bodies mounted on a supporting plate in a ring contacting part and fitting a presser bush in a center hole of a movable centripetal plate of the supporting member.

CONSTITUTION: A centripetal plate 30 moved with a material to be cut and a table plate by frictional resistance with the material to be cut when spot facing work is started and if a horizontal manual plate and a table plate are moved horizontally by a servo motor for X axis and by a servo motor for Y axis respectively. At this time a ring contact part 33 of the centripetal plate 30 is normally in a chamber 24 of a supporting member 22. If a center position of a center hole of a presser bush 38 and a center hole 20b of the presser foot 20 are dislocated when the presser foot 20 rises, the centripetal plate 30 is attracted to supporting member 22 side of a plurality of magnetic member 29 respectively. Whereby, the centripetal plate 30 is returned to a center of the center hole 20b of the presser foot 20.