A rotary sinker enabling stitch formation by a knitting machine using a rotor for forming a stitch, a knitting machine including the rotary sinker, and a stitch forming method are provided. The ring sinkers as rotating bodies are capable of rotating about a rotation axis independently of each other. The rotation times of the ring sinkers are set to be different from each other. Thus, the rotation times are adjusted to be different between the ring sinker that holds an old loop and the ring sinker that holds a new loop. Adjustment of the rotation times prevents application of a large tension to the knitting yarn made of low stretch fiber, and a stitch can be formed even with a knitting yarn made of non-stretch or low-stretch fiber.