To improve pallet indexing accuracy in a pallet exchanging position in a pallet magazine.

A pallet supporting plate 12 on which a pallet 14 is placed is connected to a chain 8 by inserting the first and second pins 18a, 18b in a round hole 12a and an oblong hole 12b and when the pallet supporting plate 12 is indexed for the pallet exchanging position of a pallet magazine, the second pin 18b inserted into the oblong hole 12b moves forward at a place from the turning part of the chain 18 to its linear part so that any distance variation between the first pin 18a and the second pin 18b owing to the curve of the chain 18 may be absorbed.