To provide a tool exchanger that is excellent in versatility and capable of quickly and easily replacing a heavy tool from a main shaft of a machine tool by human work.

The tool exchanger includes: a tool pallet guiding table provided with a guiding means capable of guiding a tool pallet 10 so as to allow a central axis of a tool held by the tool pallet 10 to be made coaxial with the axis of a main shaft 50, and adapted to allow the tool pallet 10 to freely move back and forth; a fall prevention means for preventing the tool pallet 10 from falling; tool pallet waiting tables placed adjacent to the tool pallet guiding table, adapted to allow the tool pallet 10 on the tool pallet guiding table to freely reciprocate, and provided with the tool pallet fall prevention means; and a tool pallet carriage 1 adapted to allow two tool pallets to be placed thereon, provided with the tool pallet fall prevention means, and connected to the tool pallet guiding table so as to allow the tool pallet 10 to be transferred to the tool pallet guiding table.