To provide a tool change device which changes a heavy tool from the spindle of a working machine by human work swiftly and easily.

When a tool pallet 10 is moved to connect the spindle 50 to a tool support member 19, a tool can be transferred from the spindle 50 to the tool pallet 10 through the tool support member 19. When an arm 17 is turned to keep the tool support member 19 coaxial for holding a new tool and the spindle 50 and connect them together, the new tool can be transferred from the tool support member 19 to the spindle 50. Furthermore, when the spindle 50 and the tool support member 19 are connected through an extension shaft to allow a tool support slider 18 that can advance and retreat over the extension shaft and the tool support member 19 to support the tool, the tool can be transferred between the spindle 50 and the tool support member 19.