PURPOSE: To facilitate forming of either front side or rear side of a metal sheet as well as forming in different dimensions without attaching, removing and exchanging metallic dies.

CONSTITUTION: A punch head 5 is attached movably with a striker 9, and simultaneously a cylindrical tool retainer 15 enclosing the outer periphery of the striker 9 is movably attached. An urethan rubber 19 is provided between the punch head 5 and the striker 9, and a urethan rubber 21 is provided between the punch head 5 and a punch guide. Inner recessed/projected crown members 25, 27 and outer recessed/projected crown members 29, 33 are provided by which a relative displacement in the direction in which corresponding items between the punch head 5 and the striker 9 and between the punch head 5 and the tool retainer 15 respectively come closer each other is selectively prohibited. A slide holder 49 is attached movably in the horizontal direction to the tool retainer 15, and plural punch members 51 are provided in the slide holder 49 and are used alternatively.