PURPOSE: To improve safety by constituting a driving mechanism in such a way that a driving shaft is successively projected from a driving source by a clutch contg. a brake and that a stem is driven back and forth by means of a sliding rod connected via a roller to a plate cam connected to said driving shaft.

CONSTITUTION: A rivet setter consists of an automatic revet supplying mechanism consisting of a rivet hopper 32, a rivet chute 33 and a rivet catcher 25, a curling set 19 attached beneath a caulking position via an arm 17, a stem 26 for breaking a ribet 31 by sliding upward and downward in the catcher 25 and a driving mechanism for moving upward and downward side stem. Such driving mechanism is so constituted that a driving shaft 22 is successively projected from a driving source 20 by a clutch contg. a brake and that a stem 26 is driven back and forth by means of a sliding rod 24 connected via a roller 30 to a plate cam 23 connected to the shaft 22.