A rotary seamer (1) is provided with a carousel (2) and with at least one seaming station (3) associated with the carousel (2) and comprising a rod-like element (6) rotating around its own longitudinal axis, a seaming tool (4) rotatably connected to a lever (5) integral with the rod-like element (6) and means for rotating the rod-like element (6) around its own longitudinal axis, in such a way as to displace the seaming tool (4) from an operative position, in which it interacts with an object seaming it, to a deactivated position, of non interference with the object; said means comprising an electric motor (7) associated with the carousel and kinetically to the rod-like element (6) and control means operatively active on the electric motor (7) to rotate the rod-like element (6) according to a predefined logic. In known seamers the actuation of the seaming tool is achieved by means of a cam, this entailing limitations and drawbacks in the adaptation of the seamer to the treatment of different objects.