To automatically perform an alignment highly precisely by improving a staking-punching apparatus without needing a TV-camera and a positioning mechanism being external equipment.

The press-down force of a shank-holder 9 fitted to a press mechanism P is transmitted to the staking-puncher 1. When the staking-puncher is lowered, a staking die 1a abuts on a workpiece part 4 to be staked into the forming targeted shape 5'. The staking-puncher 1 is supported to be freely displaced in a horizontal direction with a floating mechanism F. The staking-puncher 1 is lowered, and when a guide taper 1c at the lower end part of the staking-puncher is made in contact with a recessed columnar surface 2b, the staking-puncher 1 is guided with the inclining surface, and automatically aligned. When the press mechanism P is raised after finishing the plastic working of the workpiece 4, coned disc springs 17A, 17B of a separating mechanism S push up the staking-puncher 1 to separate the guide taper 1c from the recessed columnar surface 2b.