PURPOSE: To provide a switching device of a vacuum board in which a drive link is moved by a cam so that a mandrel supporter and an anvil block can be smoothly switched from one to the other by providing a mandrel-arm mounting flange with the cam.

CONSTITUTION: A first link 41 is affixed on a rotary shaft 39 which rotates an anvil block switching damper 40 and the first link 41 is pulled in one direction by a spring 45 and one end of a second link 44 is connected to the first link 41 along the opposite direction to that of pulling of the spring 45 and a drive link 46 rotated by a drive shaft 47 is connected to the other end of the second link 44. A drive bearing 48 provided at the end portion of the drive link 46 is brought into contact with a cam 49 mounted to a mandrel-arm mounting flange 3. Since the anvil block switching damper 40 is rotated by the cam 49 of the mandrel-arm mounting flange 3, backlashes and skews are prevented and cost is reduced while reliability is enhanced.