To provide an automatic replacing machine and an automatic replacing method for, a stamper of high working efficiency for carrying out speedily the replacing work for a stamper without forming soils, marks and the like on the stamper by replacing automatically a used stamper replaced by another stamper for the purpose of protecting the stamper from being brought into contact with a worker.

A clamp for fixing a stamper 7 to a mold is released by loosening automatically a clamp chuck for the stamper of a clamping mechanism 40 before the removal of the stamper 7, and the clamping of the clamp chuck of the stamper 7 is carried out through the clamping mechanism 40 after the replacement of the stamper.