To provide an automatic pallet exchanger which exchanges pallets of a tilting device.

The automatic pallet exchanger 10 in a machine tool for processing the workpiece W held by the pallet 14 includes a pallet 14 for holding a workpiece W, the tilting device 13 having a pallet 14 turning mechanism and a swing mechanism, and a table 12 to be moved in parallel with the swing shaft 13a of the tilting device 13. The exchanger is provided with a fork 1 which carries the pallet 14 between a processing position and a waiting position through rising, turning and falling action, and a fork moving mechanism having a vertically moving mechanism 5 which vertically moves the fork 1 and a turning mechanism 7 which turns the fork 1 around a vertical axis. The table 12 is moved in the axial direction of the swing shaft 13a and the fork 1 is made to engage with the pallet 14 so that the pallet 14 in a processing position and the pallet 14a in a waiting position are automatically exchanged.