PURPOSE: To absorb an impact and vibration applied on a material, to elevate a durability and to raise an accuracy by fitting a roller via a shaft to an engaging member and by providing a shock absorbing spring between a projection and groove.

CONSTITUTION: When the material to be worked is inserted into the tip opening part of an engaging part and the air is fed to an air cylinder, a shaft is extended to push up an engaging member 12 and the opening part of the tip thereof is closed to engage and hold the material to be worked. Though a large impact force is applied on the material with punching work, the impact thereof is communicated to the engaging part and engaging members 1, 2 are moved vertically according to the vibration. In this case a roller 5 is rotated along a groove 17, so the vertical motion thereof is smooth. When the engaging part is descended, a shock absorbing spring 9 absorbs the vibration of a shock due to 9' being pressed in case of its ascending. The vibration does not influence on a hollow member 20 of the supporting part of an arm 11.