PURPOSE: To provide possibility of increasing the number of tools accommodated even with a small-sized magazine, by arranging magazines to accommodate tools divided in small units outside the machine tool and by installing a relay pot to receive and hand over tools which travel between the units.

CONSTITUTION: Magazines 1, 2 storing tools, which can be driven individually, are arranged outsie the machine tool divided in small units. A relay pot 5 to receive and hand over tools between the units is moved by a transport device 4 to stop at a position for receiving or handing over tools. This pot 5 turns 90° at positions of small units and the position of replacement arm, A, to facilitate reception and handover of tools. Reception and handover of tools between the magazines 1, 2 for small units and the relay pot 5 is performed by a tool replacement device 12 while that between the relay pot 5 and spindle 11, by the replacement arm 10.