To provide a device to mechanically connect plural metal sheets which has a travel limit means of a movable tool for connection capable of easily and quickly operating.

A device is provided with a punch 1, a tool set including a die demarcating a cavity and a stopper which is driven to press/compress a sheet metal by deforming action so that a punch transfers a sheet metal stock from a surface 5 of a metal sheet 1 with the drive force produced from fluid supply and which is driven together with the punch 1 to limit a penetrating depth. The stopper consists of a closing element 22 of a valve 18 used for limiting a penetration depth and a switch bolt 14 movable to a linking device 17 for switching. The switching bolt 14 is designed for a follow element, which acts to the linking device 17 for switching, the linking device 17 for switching is released from the closing element 22 to switch a valve opening position.