PURPOSE: To make a device compact, and simplify its structure by providing an elevation member to push a pallet and engage/remove it with/from a positioning pin, and actuating the elevation member interlocked with a clamp pawl by a common clasp drive source.

CONSTITUTION: For installing a pallet P1 to a table 1, the pallet P1 is put on an elevation member 63 at a rising position, the pallet P1 is put down to the table 1 by a down motion of the elevation member 63 by a clamp cylinder 62, and a positioning recess 19 in a lower surface of the pallet is engaged with a positioning pin 20. A clasp pawl 61 is interlocked with this down motion to rotate down for pressing a down directed inner surface of a clamp groove 13 in the lower surface of the pallet, so the pallet P1 is clasped on the table 1. For replacing the pallet P1, the elevation member 63 is moved tap by the clamp cylinder 62. The clamp pawl 61 is rotated up by this to make an unclamp condition, where the pallet P1 is lifted to be removed from the positioning pin 20.