To facilitate the transverse moving control of a base seat by supporting a plurality of cam discs having a part of the transverse moving cam track of the base seat around the can holder of a cam suitable for a chain sticking sewing machine for buttonhole, and making at least two angle positions of the cam discs adjustable.

This chain stitching sewing machine cam has a non-adjustable cam disc 1 having a partial cam track 11 on the circumference. Adjustable first and second cam discs 2, 3 are fitted to the cylindrical support 12 and annular part 16 of the cam disc 1, and gears 4, 5 supported on the cam disc 1 are meshed with the internal gears 22, 32 of the cam discs 2, 3 having partial cam tracks 21, 31 on the circumferences, respectively. An overlap plate 6 is put on the second cam disc 3 from above, and the cam track positions of the cam discs 1-3 are mutually changed, whereby the length of a buttonhole is regulated.