PURPOSE: To provide a device for forming a constriction at the opening end part of a metal can.

CONSTITUTION: This device is provided with a support member 4 for pushing a can in the axial direction 6 from a bottom part 5 of a can 3, an annular anvil 8 which is placed coaxially with the support member and which has, at its prescribed part, a modeling surface 9 having a form adapted to the desired shape of the constriction at a place away from the support member, and a freely-rotating roller 10 which has a form adapted to the shape of the modeling surface, which presses the end part of the can forcefully against the modeling surface, and moreover which is carried by the support member 1 driven along a circular path concentric to the annular modeling surface by a drive means. Thus, the axis 15 of rotation of the freely-rotating roller points at least approximately in the axial direction.