PURPOSE: To stake the rivets of the same diameter and of different heights under the same conditions by carrying out the resetting of a forming tool which has finished rivet head forming after a lapse of the preset time on a timer which starts operating upon contacting of the rivet with the tool.

CONSTITUTION: An anvil 1 is set on a base 2 via an insulation material 3, and a part inserted with a rivet R is set on the anvil 1. A rivet head forming tool 6 is mounted on the bottom end of a revolving shaft 5 provided to an elevating body 4 positioned right above the anvil 1, and the forming tool 6 side and the anvil 1 are connected by an electric circuit 7 through a timer T. This timer T is started upon contacting of the forming tool 6 with the rivet R and set on the time until the forming of the rivet head is finished. As a result, upon forming of the rivet head, that is, upon a lapse of the timer T, the forming tool 6 is reset to the standby point by the elavating body 4. Thereby, the rivets with different stem lengths are staked under the same conditions without regulating stroke of the tool 6.